Answer
(a) more likely
(b) II
Work Step by Step
(a) We know that the ladder is more likely to slip as the person climbs higher because the torque exerted about the base of the ladder increases and to balance this torque, the wall and the floor exert a horizontal force in the opposite direction which increases the chances of the ladder slipping.
(b) We know that the correct option is statement (II) -- that is, the magnitude of $f_2$ must increase as the person moves upward.
