Answer:
The answer is letter A. He sets the opening of the story on a rainy day.
Step-by-step explanation:
In this excerpt of "The Metamorphosis", what makes the situation sad is the weather. We know Gregor had a bad dream, but we don't know what is was about, and the character himself doesn't seem very concerned about it. Gregor's room is described as small, but proper, even peaceful. His profession is mentioned in a natural way, not affecting the mood. But the weather helps create an emotion. It is a "dull weather", the rain hitting the window makes Gregor "feel quite sad." The weather seems to be a representation of Gregor's situation, which he hasn't realized yet. His empty life has transformed for worse - he is no longer a human, but a bug incapable of communicating.