Under 46 CFR §56.07-10, the relieving capacity of a relief valve protecting a piping system must be sufficient to prevent pressure from rising more than what percentage above the system maximum allowable working pressure?

Why C is correct

46 CFR §56.07-10(b)(2) states that the relieving capacity must be sufficient to prevent the pressure from rising more than 20 percent above the system maximum allowable working pressure. The manufacturer must certify rated relieving capacity at 120 percent of set pressure.