A piezometer opening in pipes measures

ANS:B - static pressure

A piezometer opening in pipes measures the static pressure of the fluid flowing within the pipe. A piezometer is a device used to measure static pressure, which is the pressure exerted by a fluid that is at rest. It consists of a small tube or pipe that is open to the fluid. The pressure measured by the piezometer is the static pressure of the fluid at the point where the opening is located. The static pressure measured by the piezometer represents the pressure exerted by the fluid due to its weight and the pressure exerted by the fluid's velocity. Therefore, the correct answer is: static pressure.