Final answer:
In the context of the sentence provided and the allusion to the Egyptian sphinx, the word 'pronouncement' means a wise and dignified message (B).
Step-by-step explanation:
The word "pronouncement" in the sentence 'The assistant principal watched us with the eyes of a sphinx as we listed our excuses. Then she delivered her pronouncement' refers to a formal or authoritative announcement or declaration. Considering the allusion to the Egyptian sphinx, which implies wisdom and enigma, and looking at the multiple-choice options provided, the word "pronouncement" most closely aligns with option B, a wise and dignified message. The sphinx's role in mythology, often posing riddles and judging those who attempt to answer, suggests a pronouncement that is serious and considered, rather than "an angry response", "a joke", or "a punishment".