【正确答案】 C

【答案解析】解析：ignorance(of／about)n．对……不知;无知，愚昧(如：I regret my ignorance on the subject．Ignorance of the law is no excuse．We are in complete ignorance of his plans．)。in secret秘密地(注：可以说do sth．in secret秘密做某事，不能说keep sb．in secret／in secret of)。in the dark在黑暗中；被蒙在鼓里；不让知道(注：可以说keep／leave sb．in the dark about sth．不让某人知道某事，或keep sth．in the dark对某事保密，不能说keep sb．in dark／in dark of sth．)。in quest of寻找(此处不合逻辑)。