Explanation:

- India has a Three-tier healthcare system.

- This system includes primary, secondary, and tertiary healthcare services.

- Primary healthcare focuses on basic health services through sub-centers and primary health centers.

- Secondary healthcare involves district hospitals and community health centers providing more complex care.

- Tertiary healthcare covers specialized care in major hospitals.

- Option 2: Four tier

- Not applicable. India doesn't categorize its healthcare into four levels.

- Option 3: Two tier

- Some countries have a two-tier system with public and private sectors, but India extends this further into three levels.

- Option 4: Single tier

- Implies only one level of care, not reflective of India's structured system.