Recent studies suggest that an intake of vitamin E in excess of that found naturally in a balanced diet may actually increase the risk of developing certain illnesses, despite the claims of thousands of people who swear by it as a dietary supplement.
A)Recent studies suggest that an intake of vitamin E in excess of that found naturally in a balanced diet may actually increase the risk of developing certain illnesses
B)Recent studies suggest that taking vitamin E in excess of that found naturally in a balanced diet actually increases the risk of developing certain illnesses
C)Certain illnesses may be at a higher risk of development if vitamin E is taken in excess of a balanced diet, according to recent studies
D)According to recent studies, the intake of vitamin E, if in excess of that found naturally in a balanced diet, may actually increase developing certain illnesses
E)Vitamin E, recent studies suggest, if in excess of that found naturally in a balanced diet, may actually increase the development risk of certain illnesses

How to attack such questions in less than a minute? The whole sentence is underlined and on my first read I couldn't find anything wrong with the sentence.
But to confirm I had to go over each choice horizontally to confirm and then chose A. This is how I tried doing it but it took me 1:42 sec. I am guessing its too much time for a SC question. Is there a better way to do it?

well, there's clearly no single standard for ALL SC questions. it would be foolish to allot exactly the same time limit for this problem as for a problem on which the underline is three words long.

for REALLY SHORT sc's (or for sc's with really short underlines, regardless of the length of the original sentence), you should be able to solve the problem in well under a minute.

for REALLY LONG sc's, with long underlines, you can take up to two minutes.

so, no, 1:42 is not an obnoxious amount of time for a problem like this one.