It is difficult to walk on ice because of
A. absence of friction
B. absence of inertia
C. more inertia
D. more friction

Hint: To walk, we apply Newton’s third law of motion which says every action has an equal and opposite reaction. It is relevant to walking because when you put a foot on the ground you apply a force to it and in doing so the ground also applies an equal and opposite force to your foot which helps in walking.

Complete step by step solution:
When we walk friction is observed between our feet and the ground and this friction helps from skidding off the surface and also helps to grip to the surface on which we walk. When we walk, we apply some energy for the movement of the body, but due to friction, some of the energy is wasted.
While walking, you apply a backward force on the surface on which you are standing as well as a downward force is exerted due to body weight.
The coefficient of friction is low and much less than one. A system with a low coefficient of friction has a low resistance to the surfaces sliding across one another.
The fact that ice has a very low coefficient of friction it is difficult to apply force; hence it makes it difficult to walk on the ice.

Option (A) is correct.

Note: Ice has a very smooth surface, and often it has a very thin layer of water on it; hence its coefficient of friction becomes very low. It is interesting to note here that friction is very important for the body to move, without friction we cannot even walk on the ground.