The correct answer is C. The lawyer was deceptively honest with his clients.
Explanation:
An oxymoron is a literary device in which two concepts that are contradictory by nature are put together, usually in the same sentence or by placing one beside the other. This is commonly used to include paradox and create a deeper sense. In the case of "The lawyer was deceptively honest with his clients" this is the only sentence from the options given that contains an oxymoron, because the words "deceptively honest" are contradictory and also this are place together to describe the attitude of the lawyer which also derives into a paradox as being honest means saying the truth but being deceptive is the opposite.
