The key to main point questions is to identify the main conclusion before reading the answer choices. In this case, the first sentence tells us what typically occurs in a specific situation, and the second sentence is a prescription from the author. Whenever the author is telling us what ought to be done, expect that statement to be the main point.
The final sentence is supporting the second sentence, so the final sentence cannot be the main point. Therefore, we know the main point is, "it is better that graphic designers not remain anonymous".
Answer choice C is very similar to that sentence. Answer choice D is describing the final sentence, which we identified as a premise.