Which Two PICO Components Provide the Primary Searching Terms

Which two PICO components provide the primary searching terms?

A) Problem and outcome (primary focus is on the intervention treatment and comparison treatment)
B) Intervention and comparison
C) Intervention and outcome (partially correct; intervention needs to be compared with the comparison treatment to determine which might be more effective and appropriate)
D) Comparison and outcome (partially correct; comparison needs to be compared with the intervention treatment to determine which might be more effective and appropriate)
E) None of the above