The correct option is C Deceit
The word 'honesty' refers to the quality of being honest and truthful.
Option A, sobriety refers to the quality of being staid or solemn
Option B, deceit refers to the action or practice of deceiving someone by concealing or misinterpreting the truth.
Option C, uprightness refers to the quality of being honourable and honest.
Option D, rectitude refers to a morally correct behaviour or thinking.
Thus, according to the meaning, the word 'deceit' is the opposite of the word 'honest'.