Concept:The word composure means calmness and self-control, so its opposite should describe a lack of calmness or stability.Explanation:The sentence contrasts young people with adults.While adults show composure, young people are described by a word opposite in meaning.Among the options, only “instability” means a lack of steadiness or calmness.Thus, “instability” is the most nearly opposite word and fits the gap correctly.Answer:B. instability