Explanation:

- Jitendra Singh:

- No relevant public records or announcements regarding Jitendra Singh being appointed as the Chairman and Managing Director of Telecommunications Consultants India Limited (TCIL) in January 2021.

- Rajeev Kumar:

- Similar to the first option, no significant information supports Rajeev Kumar's appointment to this specific role in 2021.

- Sanjeev Kumar:

- Correct Answer

- Sanjeev Kumar was appointed as the Chairman and Managing Director of Telecommunications Consultants India Limited in January 2021. His appointment focused on enhancing strategic initiatives at TCIL.

- Sarabjit Singh Sandhu:

- There are no substantial details linking Sarabjit Singh Sandhu to the position of Chairman and Managing Director at TCIL in the given timeframe.

Therefore, Sanjeev Kumar is the correct choice, recognized for his leadership capacity in this telecom consultancy company.