C

Explanation:
The Completer/Finisher role in Belbin’s framework is responsible for ensuring tasks are completed on time and to a high standard, often acting as a progress chaser. This role is necessary but can be unpopular due to its focus on deadlines and perfectionism. Option A (Implementer) focuses on organizing tasks, option B (Resource Investigator) on networking and ideas, and option D (Co-ordinator) on delegating and leading. Therefore, C is the correct answer.