Determine the correctness or otherwise of the following Assertion (a) and Reason (r).
Assertion (a): During welding of aluminium alloys by the gas tungsten arc welding process, direct current reverse polarity (DCRP) mode is used.
Reason (r): DCRP facilitate breaking up of the oxide film on the workpiece surface.

A. a is true but r is false

B. a is false but r is true

C. both a and r are true, and r is the reason for a

D. both a and r are true, and r is not the reason for a

Answer: Option C