API RP 571 identifies these parameters as critical to the corrosion rate of carbon and low alloy steels in sour water environments:
"The extent of corrosion in sour water is influenced by pH, H#S content, temperature, liquid velocity, and oxygen contamination."
"These factors control the formation and stability of protective iron sulfide layers." (Reference: API RP 571, Section 4.3.2.1 - Sour Water Corrosion) Therefore, the correct answer is A.