Consider the following statements regarding torque converter:
1. it has a stationary set of blades in addition to the primary and secondary rotors.
2. It can be used for multiplication of torques
3. The maximum efficiency of a converter is less than that of a fluid coupling.
4. In a converter designed to given a large increases of torque, the efficiency at smaller speed ratio approaches unity.
(a) 1,2,3 and 4 (b) 1,2 and 3
(c) 1,2 and 4 (d) 3 and 4