Concept:The sentence needs a past modal form to show that issuing the cheque was a wrong or unwise action already completed.
Explanation:The dismissal happened because of a past action: he issued the cheque.
“Should not have issued” expresses blame or regret about that past action.
“Must not issue” and “ought not to issue” refer to present or future obligation, not to a past mistake.
“Will have issued” talks about a future completed action, which does not fit the past context.
Therefore, the correct answer is option C.
Answer:C. should not have issued
The completed sentence is: He was dismissed because he should not have issued the cheque.