New hardy varieties of rice show promise of producing high yields without costly requirements of irrigation and application of commercial fertilizer by earlier high-yielding varieties.

A) requirements of irrigation and application of commercial fertilizer by earlier high-yielding varieties.
B) requirements by earlier high-yielding varieties of application of commercial fertilizer and irrigation.
C) requirements for application of commercial fertilizer and irrigation of earlier high-yielding varieties.
D) application of commercial fertilizer and irrigation that was required by earlier high-yielding varieties.
E) irrigation and application of commercial fertilizer that were required by earlier high-yielding varieties.

OG answer - E. Could you please explain the grammatical glitch?

Thanks

"without costly X" - that X should be whatever is costly, in this case irrigation and application of fertilizer. Putting "requirements" next breaks the flow of this statement. Eliminate A, B, C.

D says "application... and irrigation that was" - this should be plural (compound subject)

E correctly puts irrigation and application after costly and also correctly uses "were" to refer to the compound subject.

do i have to login in this forum? i cannot register or login?

Nope, you don't have to register. When you post, you just type in whatever ID you want - if you want to keep using the same one, then just keep typing it in every time you post.