Sentence correction questions are usually best tackled by reading the initial sentence, looking for the errors that we know GMAT test writers like to test for. In this case we can see that the sentence says:

"the drawings...shows the buildings..."

So we can safely eliminate (A) and (B).

Let's also suppose that you have heard that the word being is wrong (not 100% true), so you eliminate (D). How can you choose between the remaining two choices?

A simple rule of thumb is that shorter answers tend to be better than longer answers. So (C) must be our leading candidate for the best answer. Unless we find something objectionable about (C), we should select it at the best choice.

I find nothing wrong with (C) at all. It is clear and unambiguous.