Consider the following statements:
1. The friction factor in laminar flow through pipes is independent of roughness.
2. The friction factor for laminar flow through pipes is directly proportional to Reynolds number.
3. In fully turbulent flow, through pipes, friction factor is independent of Reynolds number.
Which of the statements given above are correct?
a. 1, 2 and 3 b. 1 and 3 only
c. 2 and 3 only d. 1 and 2 only