c
(c) To avoid slipping one should take smaller steps because the frictional force of ice is small.

Smaller steps will give larger normal force and more the normal force more the friction.

Also the advantage of talking small steps is that lateral forces are decreased. When we put down are foot it will be pushing forwards on the concrete and at the end of the step it will be pushing backwards. Hence larger the step these forward and backward forces will be larger increasing the chances of slipping.