[单选题]
An electric motor is us-dpzcf /tn p.typml1a:dv , -;ed to uat6+ 4c73aicluxr(u r ik/ l+raise a block of mass 18.0 kg vertically to the top of a building at a constant speed o uca+i43lxuia+lr7uk (t/rc6f $1.5\,ms^{−1}$. If the power rating of the motor is 297 W, calculate the efficiency of the motor.
