Answer:
A. Active
Explanation:
When trying to decide if a sentence is using active or passive voice, look where the "doer" is located in comparison to the verb. The "doer" is the subject performing the action. In this sentence, the "doer" is Steven since he is the one performing the action, i.e. climbing the ladder.
When the "doer" is located before the action, the sentence is typically active.
When the "doer" is located after the action, the sentence is typically passive.
In this sentence, since the "doer" (Steven) is located before the action, (climbed the ladder) the voice is active. If the sentence was passive, it would read, "Without thinking, the ladder was quickly climbed by Steven."
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