Based on the given data, how does the energy used in biking 1 km compare with that used in walking 1 km? Biking takes

(a) 1/3 of the energy of walking the same distance;

(b) The same energy as walking the same distance;

(c) 3 times the energy of walking the same distance;

(d) 9 times the energy of walking the same distance.

On flat ground, a 70-kg person requires about 300 W of metabolic power to walk at a steady pace of 5.0 km/h(1.4 m/s). Using the same metabolic power output, that person can bicycle over the same ground at 15 km/h.