API RP 578 (Material Verification Program), referenced in API RP 571, specifically calls out sulfidation failures as a major driver for Positive Material Identification (PMI):
"PMI programs are particularly important in services prone to sulfidation where incorrect alloying elements (e.
g., carbon steel used in place of low Cr alloy) have led to catastrophic failures."
"Many failures have occurred when carbon steel was mistakenly installed in place of specified Cr-alloys in sulfidation-prone environments." (Reference: API RP 578 and API RP 571, Section 4.2.1.1 - Sulfidation) Thus, option C is the most appropriate answer.