Fill in the blank with an appropriate preposition. The thunder was accompanied…

Answer: by

Correct sentence: The thunder was accompanied by a heavy rain.

Note: It is more natural to omit the article and say 'The thunder was accompanied by heavy rain,' but given the sentence as written, 'by' is the correct preposition to show co-occurrence.

Explanation: 'Accompanied by' is the standard construction to indicate that one thing occurs together with another.

• from — indicates origin or source, not simultaneous occurrence, so it does not fit here.

• Up — irrelevant in this context and not used with 'accompanied' to mean 'occurred together'.

• Through — suggests movement across or within something, not co-occurrence; it does not convey the intended meaning.

Therefore, 'by' is the best choice because it correctly expresses that the thunder occurred together with the rain.