The work done against friction when moving a body by a distance d is given by the formula: W=Ff⋅d where W is the work done against friction, Ff is the force of friction, and d is the distance moved. The force of friction Ff can be calculated as: Ff=µ⋅R where µ is the coefficient of friction and R is the normal reaction force exerted by the surface on the body. Substituting the expression for Ff into the work formula gives: ‌W=(µ⋅R)⋅d ‌W=µRd Therefore, the correct answer is: Option A: µ‌Rd.