obtained from a manhattangmat exam question:

A higher interest rate is only one of the factors, albeit an important one, that keeps the housing market from spiraling out of control, like it did earlier in the decade.
Correct Answer: B. keep the housing market from spiraling out of control, as it did

I thought the verb was singular, "keeps", in referring to "interest rate" as the subject. However, the explanation says it's "keep" because the subject is "factors" which is plural. I'm having trouble understanding that the subject is factors and not interest rate. Aren't we talking about interest rates here? Please explain.

I really appreciate it. This one really gets me.

Please remember to
- post in the appropriate folder (in this case it should go in the MGMAT CAT Verbal folder)
- post the entire text of the question, including all answer choices
- follow the naming convention in the appropriate folder (eg, in this case, it should be in the CAT Verbal folder and the name should be the first 5-8 words of the question)

I think I can answer your question based only on what you've typed because I'm familiar with the question, but if you have further questions, please post the full text.

"interest rate" is the subject and the verb that goes with "interest rate" is the word "is," which is also singular. The word "that" right before the word "keep/s" introduces a noun modifier, and this noun modifier refers to the closest preceding primary noun. Interest rate is not that noun - factors is.

The core of the sentence is:
A(n) interest rate is one of the factors that keep...
[main subject] [main verb] [object] THAT [noun modifer, referring to object]

The big question is really: should the noun that matches with keep/s be "one" or "factors"? In this special case, you have to look at the meaning of the sentence. What is preventing the housing market from spiraling out of control - just the one factor, the higher interest rate, or the combination of factors, plural? In this case, it's the latter, so we match "keep" with "factors."

stacey- can we have an expert opinion on the following..
"A higher interest rate is only one of the factors, albeit an important one, that keeps the housing market from spiraling out of control, like it did earlier in the decade"

i think the phrase "only one of the factors.." suggests that plural should be used. EX:

1. Tom is one of my friends who is coming to dinner tonight => i have lot of friends, Tom is one of them and he is coming over.

2. Tom is ONLY one of my friends who ARE coming to dinner tonight=> there are a bunch of people coming tonight- Tom is one of them.

does this make sense?

thx

Sorry. I correctly file the questions according to the topic now!

I got the question from one of ManhattanGMAT's CAT's. It came up again today! And I made the same mistake! But after reading your response, I better understand the correct split between "keeps" and keep", the correct answer being "keep".

Do you know if this comes up often?

Thanks again for your reply. Your explanations are really helpful!

Rohit, I agree that the placement of the word "only" here should be a clue that we are likely dealing with a plural situation.

The wording of your first sentence is ambiguous - we would speak this way but it wouldn't pass GMAT muster. Is the "of my friends" phrase in that sentence talking about friends who are not coming to dinner, friends who are coming to dinner, or a mix of the two? I don't know and, since I don't know, I can't decide what to use for the verb. To make it unambiguous, I'd have to say something like, eg, Tom, one of my friends, is coming to dinner tonight.

Or, of course, you can make it unambiguous by saying Tom is only one of the friends who are coming to dinner tonight.

Guest612, I'd say that a question may touch on this issue about half the time (that is, every other person could expect to see something like this). It will generally show up on harder questions and there will also be other ways to narrow down your choices.