The right answer is Plucking.
A glacier has several means of action to imprint its mark on the landscape. In the first place, the ice that composes it can act:
* By pushing, which causes fracking and tearing protruding reliefs on the bed, thus giving rise to tearing abrupt,
* By abrasion, below the bergschrund for a circus glacier and on the bottom and walls of the trough of a valley glacier. Abrasion often gives rise to moutonne rocks.
* Lastly, by polishing, which gives rise to glacial polis.
