💡 Detailed Explanation
"潔い" (isagiyoi) describes an attitude of admitting a mistake or defeat frankly and without making excuses, in a way that is considered admirable. It's the best fit for someone who takes responsibility properly. "素直" (sunao) means obedient or honest, but it lacks the nuance of "admirable courage." "あっさり" (assari) means to do something readily or without resistance, which can feel too light for a serious mistake. "単に" (tan ni) means "simply" or "merely" and does not fit the context.