Consider the following statements:

Two rotors mounted on a single shaft can be considered to be equivalent to a geared-shaft system having two rotors provided 1). the kinetic energy of the equivalent system is equal to that of the original system 2). the strain energy of the equivalent system is equal to that of the original system 3). the shaft diameters of the two systems are equal Which of these statements are correct?

(a) 1,2 , and 3

(b) 1 and 2

(c) 2 and 3

(d) 1 and 3 .