NAHQ defines FMEA as a proactive risk assessment tool used to anticipate how a process might fail before harm occurs. The first foundational step in an FMEA is to clearly define and map the process, typically through a process flow diagram.

Without a shared understanding of each step in the procedure, the team cannot accurately identify potential failure modes or downstream effects. RCA (Option C) is a reactive tool used after events occur. Run charts (Option A) and adverse event review (Option D) may inform risk awareness but do not replace process mapping. Therefore, developing a process flow diagram is the essential prerequisite, making Option B correct.