After using for some time, big transformers get heated up. This is due to the fact that
1. the current produces heat in transformers
2. occurs in the hysteresis loss transformers
3. liquid used for cooling gets heated
Select the correct answer using the code given below.

Options

A. 1 only
B. 2 and 3 only
C. 1 and 2 only
D. 1,2 and 3