Valves, regulators and pressure switches come into picture while considering _________

A)
solid rocket engines
B)
liquid rocket engines
C)
both solid and liquid rocket engines
D)
neither solid nor liquid rocket engines

Correct Answer :   liquid rocket engines


Explanation : Valves, regulators and pressure switches are required for controlling and regulating the flow of liquid propellants in rocket engines which use them. The use of such equipment adds to the complexity of liquid propellant rocket engines compared to other types.