Correct answer: B. trusting

Explanation:
"Trusting" is the correct choice because it describes someone who appears easily believable or trustworthy, fitting the description of an expression that gives the impression of honesty. However, it contrasts with the fact that the person actually has a "very devious mind," creating a deceptive contrast.
Meaning of other options:
A. competent: Refers to someone skilled or capable, which does not describe an expression.
C. integrated: Refers to something unified or whole, not suitable for describing an expression.
D. integrity: Refers to honesty or strong moral principles, but it is a noun and does not fit grammatically in this sentence.
Dịch: Anh ấy có một vẻ ngoài trung thực và đáng tin cậy, che giấu thực tế rằng anh ấy có một tâm trí rất xảo quyệt.