Which of the following statements is true about the IS-IS backbone area?

Which of the following statements is true about the IS-IS backbone area?
A . A router belongs to all areas.
B . All routers belong to the same area.
C . This area comprises a series of continuous L2 routers and L1-L2 routers.
D . This area is central area connected to other areas.

Answer: C

Explanation:

Reference: https://www.sciencedirect.com/topics/computer-science/internal-router