With decrease in the grain size of a material, its creep resistance

ANS:C - remains constant.

In materials science, when the grain size decreases, the creep resistance typically increases, as I mentioned in the previous response. This is because smaller grain sizes hinder the movement of dislocations, which are responsible for plastic deformation and creep. As a result, materials with smaller grains are less prone to creep deformation, leading to improved creep resistance. Therefore, the correct statement would be that with a decrease in grain size, the creep resistance of a material usually increases.