Which of the following senses is most closely related to balance

a. touch
b. taste
c. smell
d. hearing

D. HEARING is the sense most closely related to balance.

We maintain our balance through the detection of the movement of the fluid in our inner ear by hair cells.

Our inner ear has three semi-circular canals that are full of movable fluid and sensory hairs that are moved when the fluid moves. These tell you which way your head and body is tilted in relation to gravity and give you information about movements and acceleration. Thy are also incidentally partially responsible for sea-sickness when the  brain is fed conflicting information about the world from your ears and your eyes, the reason why you should get off your bed and go on deck to look at the horizon so the information matches.

It is used to during sexual reproduction between humans