One of Freud's great______into the human personality was the discovery of how it is influenced by unconscious processes.

【正确答案】 C

【答案解析】本题空格处是说对人类性格的洞察力。insight“深刻的了解，洞察力”符合题意。conviction“深信，确信”。concept“观念，概念”，instinct“本能”都不正确。