The force required to row a boat over the sea 
is proportional to the speed of the boat. It is 
found that it takes 24 h.p. to row a certain 
boat at a speed of 8km/hr, the horse power
required when speed is doubled - 
(A) 12 h.p. 
(C) 48 h.p. 
(B) 6 h.p. 
(D) 96h.p.