The correct answer is C – Conduct retrospectives at the end of every sprint.

According to the Agile framework, regular retrospectives are a key practice to inspect and adapt the process. If team members have concerns about the Scrum Master's processes, the appropriate time and space to bring up and resolve such issues is the Sprint Retrospective.

From the PMI Agile Practice Guide:

“Retrospectives are a time-boxed event that enables the team to inspect itself and create a plan for improvements to be enacted during the next iteration. It provides a structured opportunity for feedback and reflection.”

(PMI Agile Practice Guide, Section 3.5, Iteration Retrospectives)

Mike Griffiths further adds:

“Teams must take ownership of their process. The role of the agile leader, such as a Scrum Master, is to facilitate improvement via mechanisms like retrospectives. They are not responsible for enforcing process, but for enabling continuous improvement.”

(Mike Griffiths, PMI-ACP Exam Prep Book, Chapter 4 – Team Performance)

Why the other options are incorrect:

A may undermine the team's self-organization and brings hierarchy into team-level process adjustments.

B may address some confusion, but doesn’t actively involve the team in process improvement.

D is inappropriate—sprint planning is for work planning, not process feedback.

Therefore, the most agile-appropriate and validated solution is: C

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