Correct Answer & Explanation
Option B
• The word 'since' introduces a point in the past from which an action or state has continued up to the present.
• This indicates a connection between a past event (joining the post) and a present state (not taking bribe).
• The Present Perfect Tense is used for actions that started in the past and continue or have an effect in the present.
• Therefore, 'has' (as in 'has not taken') is the correct auxiliary verb for the Present Perfect Tense.