Concept:An opposite word must fill the gap while giving the reverse meaning of the underlined word.Explanation:The underlined word in the sentence is "incompetence".Incompetence means lack of ability to do a job successfully.It is the direct opposite of efficiency, which means working in a well-organized and competent way.The other options do not match the opposite idea: punctuality, honesty, and sincerity are not about ability.Answer:C. efficiency