When We Apply the Energy Conversation Principle to a Cylinder

Multiple Choice

When we apply the energy conversation principle to a cylinder rolling down an incline without sliding, we exclude the work done by friction because:

A) there is no friction present
B) the angular velocity of the center of mass about the point of contact is zero
C) the coefficient of kinetic friction is zero
D) the linear velocity of the point of contact (relative to the inclined surface) is zero
E) the coefficient of static and kinetic friction are equal