Answer:
The complex sentence here is sentence A
Step-by-step explanation:
Let's look at b and c.
Option B: Late too much for dinner- This is improper grammar and therefore a VERY simple sentence.
Option C: Felix spent most of his junior year doing charity work for the United Way. This is considered a simple sentence because you can't put it into 2 seperate sentences. What I mean is, I like cupcakes. That's a simple sentence. I like cupcakes, and cookies. That is a complex sentence.
Option D: It can't be correct since we already know that Option B and C are simple sentences.
Hence, the answer is A