Hi eybrj2,
Thank you for your question. This is a tricky one, so let's tackle it one problem at a time. When looking over the answers quickly, it's clear there are a couple differences we can address to narrow down answers:
1. the use of "increasingly" vs. "more"
2. the use of "increases" vs. "getting larger"
So the trick with this sentence is to decide which part gets to use the word "increase": the growing intensity of the problem or the change in size of the space. Since it makes more sense to use the word "increase" to show the growing size of the space, let's take out any answers that use a version of "increase" to describe the problem. This means we can rule out answers A & D.
Now that we're left with answers B, C, & D, let's check for one of the most common errors in GMAT sentence correction questions - parallel format. In this case, the parts in bold need to be parallel in format and style to the original verb "becomes." Let's see how they stack up:
(b) becomes / ever more critical as the size of the space
increases (CORRECT = parallel format) (c) becomes / more and more critical as the size of the space
will increase (WRONG = not parallel) (d) becomes / one that is increasingly critical
as there is an increase in the size of the space
(WRONG = not parallel)So, based on the more appropriate use of "more" instead of "increases," and based on the correct parallel format, it's clear that
B is the correct answer.