In preparation for an upcoming law school entrance exam, I've been taking a number of practice tests, sections of which being English Proficiency. On one of them, I came across this item:
Directions: Choose the answer which will produce the most effective sentence.
When Leonard was just starting to work out, he was given a limited choice of which food to eat--fruit smoothie, vegetable salad, or soup.
A) he was given a limited choice of which food to eat
B) he was given a limited choice of food to eat
Apparently, the correct answer was B. However, the reviewer does not provide the grammar rules that dictate the answers to its items, so I've come here.
What are the rules when using an "a choice of..." phrase? When is it right to use the word "which"?