Answer:
B) When Patricia saw that she had Mrs. Crenshaw on her schedule, she despaired; everyone knew that Mrs. Crenshaw assigned more homework than any other tenth grade English teacher.
Step-by-step explanation:
Semicolons separate two related sentences. Using a comma between "despaired" and "everyone," or not using punctuation at all, would cause it to be a comma splice or run-on sentence. D is a very close answer because the conjunction "and" can also connect two sentences, but only with a comma before it. Plus, it would just be wordy. :)