The correct option is B Credulous
Option B: 'Credulous' means 'having or showing too great a readiness to believe things'. This word means the same as the given expression and hence option B is correct.
Option A: 'Credible' means 'able to be believed, convincing'.
Option C: 'Sensible' refers to good judgement and means 'full of common sense'.
Option D: 'Sensitive' means 'quick to detect or respond to slight changes or signals'.
These words do not mean the same as the given expression. Hence options A, C and D are wrong.