Riding a bicycle requires balance and constant

adjustment and monitoring by the rider in order

to continue cycling. Successfully riding a bicycle

most directly results from the ability to

(1) sexually reproduce

(2) grow and develop

(3) detect and respond to change

(4) metabolize food for energy

The answer is (3) detect and respond to change.

The fact that riding a bicycle requires "constant adjustment and monitoring by the rider in order to continue cycling" means that the body needs to be able to A) sense changes in balance and speed and B) quickly respond to those changes so that you don't fall off your bike.