The correct answer is: A. with
The word “with” is used to indicate that two things are happening at the same time. In this case, the thunder is happening at the same time as the heavy rains.
The word “by” is used to indicate that one thing is caused by another. In this case, the heavy rains are not caused by the thunder.
The word “through” is used to indicate that one thing passes through another. In this case, the thunder does not pass through the heavy rains.
The word “up” is used to indicate that something moves in a higher direction. In this case, the thunder does not move in a higher direction.