Consider the following statements:
In electrochemical grinding.
1. A rubber bonded alumina grinding wheel acts as the cathode and the work piece as the anode.
2. A copper bonded alumina grinding wheel acts as the cathode and the work piece as the anode.
3. Metal removal takes place due to the pressure applied by the grinding wheel.
4. Metal removal takes place due to electrolysis.
Which of these statements are correct?
(a) 1 and 3 (b) 2 and 4
(c) 2 and 3 (d) 1 and 4