Manhattan GMAT Verbal Study Guide - SC Question No. 18

[piyush]

In an effort to shorten the time span and cut the costs needed to grow full size beef stock, many ranchers substitute cornmeal and ground bones for their cattle's regular diet, branded by them to become generic-grade beef

(A) for their cattle's regular diet, branded by them
(B) for the regular diet of their cattle which have been branded
(C) for the regular diet of their cattle, having been branded
(D) in place of their cattle's regular diet, for those of them branded
(E) in place of the regular diet of their cattle to have been branded by them

I was able to eliminate D and E because "substitute for" is the correct idiom. In Choice A "branded by them" seems to modify "diet". However neither choice B nor C seemed to make sense. I eliminated B because "which" is a non-essential modifier and should be separated by a comma. But the correct answer choice is B. Can you please explain?

Thanks,

[RonPurewal]

Choice C, which makes use of a present participle, implies that the ranchers themselves have been branded to become generic-grade beef. (I wonder how that would taste?)

Choice B would probably be a little better with 'that' instead of 'which', but the clause is essential (so it shouldn't have the commas). You know the clause is essential because not ALL of the cattle are branded to become generic-grade beef; therefore, the clause refers only to those cattle that ARE destined to that fate.