The implicit detail that is best supported by this passage is option D: The characters were scared of the storm.
A. The rain had started to fall: This is explicitly stated in the passage.
B. The characters peered out the window: This is also explicitly stated in the passage.
C. Something was chasing the characters: This is not supported by the text. There is no mention of any predator other than the storm itself.
D. The characters were scared of the storm: This is implied by several details:
The imagery of "running from a predator" and "huddling in the corner" suggests fear.
The characters "shudder" each time the thunder rumbles, further indicating fear.
Therefore, option D is the most accurate inference based on the clues provided in the passage.