Power equals work divided by time Steps:

• Work done against gravity to lift the load is force times distance: W × d.
• Useful power P is work divided by time taken t: P = (W d) / t.
• Rearrange for time: t = (W d) / P.
• For constant velocity, velocity v = d / t = P / W, but the expression matching t is W d / P.

Why C is correct:

• It equals time t = work / power from the definition of power as rate of work done.

Why the others are wrong:

• A: P / (W d) = 1 / t, the inverse of time.
• B: W v equals power P for constant-velocity lifting.
• D: P v / W has units of velocity squared and circularly includes v.

Final answer: C