The correct answer is: D. decision
He admired precision in everything, but it never hampered his quick decision. This means that he was able to make quick decisions even though he always wanted to be precise.
Option A, finalisation, is incorrect because it does not make sense in the context of the sentence. The sentence is about how he was able to make quick decisions, not how he was able to finalize things quickly.
Option B, dealing, is incorrect because it does not make sense in the context of the sentence. The sentence is about how he was able to make quick decisions, not how he was able to deal with things quickly.
Option C, action, is incorrect because it does not make sense in the context of the sentence. The sentence is about how he was able to make quick decisions, not how he was able to take action quickly.