The correct answer is A. Evening.

Thunder is often associated with rain, and evening is often associated with night. Both thunder and evening are often seen as precursors to something else, and both can be seen as a time of transition. Thunder is often seen as a warning of an approaching storm, and evening is often seen as a time when the day is coming to an end.

The other options are not as closely related to their respective words. Evening is not as closely related to dark as thunder is to rain. Day is not as closely related to dusk as thunder is to rain.