Question

As soon as the doors were opened, a flurry of activity ensued.

• A. As soon as they opened the doors, a flurry of activity ensued.
• B. When the doors were opened, it was followed by a flurry of activity.
• C. No sooner were the doors open, than a flurry of activity ensued.
• D. Hardly had the doors opened, than a flurry of activity ensued.
• E.

Hint:

In constructions involving cause and effect, use “as soon as” for clarity and conciseness.

Answer 1

The Correct Option is A

The sentence indicates that once the doors were opened, immediate action followed. - Option (A) "As soon as they opened the doors, a flurry of activity ensued" keeps the original meaning intact and conveys the sequence of actions clearly. - Option (B) “When the doors were opened, it was followed by a flurry of activity” is grammatically correct but does not flow as naturally as Option A. - Option (C) and Option (D) involve more complex constructions that are less direct than Option A. Therefore, the correct choice is “As soon as they opened the doors, a flurry of activity ensued” (Option A). 

Answer 2

Since the goal is to prefer a direct, natural-sounding construction over passive or overly formal alternatives when meaning stays intact, testing each option for both grammatical correctness and naturalness of phrasing settles the choice.

1. Option A: "As soon as they opened the doors, a flurry of activity ensued" converts the passive "doors were opened" into an active "they opened the doors" while keeping the "as soon as...ensued" sequence, reading naturally and preserving the original timing and meaning.
2. Option B: "When the doors were opened, it was followed by a flurry of activity" retains a passive structure throughout and uses "it was followed by," which is grammatically valid but noticeably more roundabout than necessary.
3. Option C: "No sooner were the doors open than a flurry of activity ensued" introduces the inverted "no sooner...than" construction, which changes the sentence's register to a more formal, literary structure not required here.
4. Option D: "Hardly had the doors opened, than a flurry of activity ensued" similarly forces an inverted "hardly had...than" construction and additionally places a comma before "than" in a way that is not standard.

Option A achieves the clearest, most natural rendering of the original sentence without unnecessary passive voice or forced inversion.

Hence, the correct answer is Option A.