The sentence "The wind had savage allies." serves as an opening hook, indicating that other destructive forces accompanied the wind. The immediate next sentence should reveal one of these allies in a vivid and dramatic manner.
Sentence B — "The first clap of thunder came as a deafening explosion that literally shook my teeth." — fits perfectly as it describes thunder in a powerful, sensory way. This follows logically from the idea of "allies" of the wind, presenting thunder as the first one.
After B, sentence C — "I didn’t hear the thunder, I actually felt it — an almost unbearable physical experience." — naturally expands on the previous line by shifting from the sound of thunder to its intense physical impact, reinforcing the danger and ferocity of the storm.
Next, sentence A — "If it had not been for my closely fitted helmet, the explosions might have shattered my eardrums." — flows well as it reflects on the protection required to withstand the violent thunderclaps, continuing the same chain of thought about the effects of the storm.
Finally, sentence D — "I saw lightning all around me in every shape imaginable." — adds another visual and dramatic element to the storm’s fury, complementing the auditory and physical descriptions. This leads naturally to sentence 6, which focuses on the torrential rain, completing the sequence of dangerous "allies" (thunder, shockwaves, and lightning) before the rain.
Thus, the correct sequence is B → C → A → D, matching option (a) BCAD.