Consider the following statements regarding power screws.
1. The efficiency of self locking screw cannot be more than 50%
2. If friction angle is less than the helix angle of the screw, then the efficiency will be more than 50%.
3. The efficiency of ACME (Trapezoidal thread is less than that of square thread.
Which of these statements are correct?
(a) 1, 2 and 3 (b) 2 and 3
(c) 1 and 3 (d) 1 and 2