Who is responsible for the development of surveillance activities?

Comprehensive and Detailed In-Depth Explanation:

According to ISO 17021-1:2015, Clause 9.6.2 (Surveillance Activities):

The certification body is responsible for planning and conducting surveillance audits to ensure continued compliance.

The auditee’s top management (A) does not develop surveillance activities, but they must participate.

The audit team leader (C) conducts the surveillance audit, but they do not develop the program.

Thus, B is the correct answer.