[单选题]
An electric motor isechp :,db i6p1kko) k9 uf hm: m8gzty+l6 )fw04kg1y fgsed to raise a block of mass 18.0 kg vertically to the top of a building at a constmk +y gfzg6tw:148yf)fmglh0 ant speed of $1.5\,ms^{−1}$. If the power rating of the motor is 297 W, calculate the efficiency of the motor.
