Which of the following materials of the propellant tank requires a thin inner liner of metal to avoid leakage?

A)
Titanium
B)
Aluminum
C)
Stainless steel
D)
Fiber-reinforced plastics

Correct Answer :   Fiber-reinforced plastics


Explanation : Fiber reinforced plastics can have tiny pores through which the propellant can escape easily. In order to prevent that, it is coated with a thin layer of some impervious metal.