Concept:"Decisive" refers to something that firmly settles an issue or has an important effect on the final result.
Explanation:In the expression "decisive action," the word "decisive" describes action that is firm and strong enough to bring about a clear outcome.
Such action is usually taken at an important moment, so it carries great significance.
The word "significant" means important, meaningful, or having a notable impact on a situation.
This is the closest meaning among the options provided.
"Inconclusive" means leading to no definite result, which is opposite to being decisive.
"Indecisive" also means unable to make firm decisions, so it is another opposite.
"Trivial" means unimportant, which does not fit the idea of a firm and outcome-determining action.
Therefore, the word that is nearest in meaning to "decisive" is "significant".
Answer:A. significant