GMAT Sentence Correction: Conditional Statements

GMAT Sentence Correction will test your comprehension of the sentence’s meaning as well as its grammar, style, and concision, by giving you more answer choices that are grammatically correct (but still wrong). Let’s explore the ways this can happen.
 

If you are very hungry, you eat too much food.
If you are very hungry, you may eat too much food.
If you are very hungry, you will eat too much food.
If you are very hungry, you should eat too much food.
 
Conditional statements in English have many different combinations of tenses and moods, which could be the subject of a whole series of blog posts on its own. Instead, I’ve chosen a subset of conditions here, each with a slightly different verb in the “then” clause.
If you are hungry, you eat too much food. This form is common enough, usually appearing in sentences announcing the result of a study or report (A recent Harvard Medical School study has conclusively shown that if you do not eat, you die). In English, when both parts of the condition are in the simple present tense, it refers to a statement of general truth; whenever the first thing happens, the second thing happens (When I get caught in the rain, I get wet).
If you are very hungry, you may eat too much food. By introducing the modal auxiliary verb may, we have added uncertainty, possibility, or permission to the sentence; eating too much food is something that you will not certainly do in all circumstances. It could either indicate one of several options (We may go to the festival tomorrow) or that permission has been granted (You may stay in my home for as long as you like).
If you are very hungry, you will eat too much food. In exchanging the present tense for the future tense in the “then” portion, we have changed our statement of general truth into a specific prediction about the future: if X is the case, Y will certainly happen (If it is raining right now, you will be soaked by the time you reach your car).
If you are very hungry, you should eat too much food. Finally, by putting in the modal auxiliary verb should, we have made overeating an obligation, something that is right or good (If you see your boss at lunch time, you should ask for some vacation time this summer). Now let’s try a sample question.
 



A. Incorrect. It is fine grammatically, but there is no reason to put a modal “should” in the second half of the condition. It’s already a prediction about the future, a prediction which may not come to pass; adding even more uncertainty to the “then” portion is not needed to convey that.
B. Incorrect. I suppose this was mean of me; by changing the beginning and end of one answer choice, I had an excuse to increase the length of the underlined portion and make you read more for every answer choice. This choice is technically correct as well, but I think it would only be a strange alternate universe where the GMAT wanted you to use phrases like “can continue its increasing.”
C. Incorrect. This one is the present/present tense trap that I mentioned, which is entirely grammatically correct and appropriate for studies. Here, though, the meaning is changed, claiming that WHENEVER interest rates remain at their current level, lending will increase at some (slow) rate. While a study could show that, it would not come in the form of a prediction.
D. Correct. Here we have a simple present for the static interest rates and a simple future for the predicted effect.
E. Incorrect. As with Choice A, the modal “could” is grammatically and even contextually plausible, but there is no reason to add this additional uncertainty to the prediction.