ANS:B - parallel to web

Twisting takes place about the axis which has less moment or inertia or least radius of gyration because that axis offers maximum critical load.

In general, channels are weak or has less moment of inertia about the axis which is parallel to the web. Hence, they may buckle or twist about that axis.

Flanges are stronger in resisting bending and twisting moments as compared to web. Hence, there is less chance of twisting in flanges. Hence, the most appropriate option would be '2'.