Consider the following methods:

(1) Trifilar suspension

(2) Torsional oscillation

(3) Fluctuation of energy of engine

(4) Weight measurement and measurement of radius of flywheel Which of the above methods are used to determine the polar mass moment of inertia of an engine flywheel with arms?

(a) 1 and 4

(b) 2 and 3

(c) 1,2 , and 3

(d) 1,2 , and 4 .