According to Pollution Prevention Regulations (33 CFR), the minimum number of bolts permitted in an ANSI standard flange on an oil hose is __________.

Correct Answer: Option B — four

33 CFR 156.120 requires that every flange in an oil transfer system must be fully bolted. For standard ANSI flanges, this means a minimum of four bolts must be used to ensure an even, pressure-tight seal across the gasket, preventing potential leaks during high-pressure transfer operations.