Balance Everyone Knows That Your Ears Are Responsible for Your Sense

Balance
Everyone knows that your ears are responsible for your sense of hearing. But did you also know that your ears are also partially responsible for your sense of balance? Your inner ear contains something called the vestibular system, which is a key component in your body's ability to establish and maintain balance.
The vestibular system mainly consists of three semicircular canals. Each semicircular canal has a different orientation, allowing them to detect a variety of movements. The canals are filled with a fluid called endolymph. When you move your head, the fluid in the canals also moves; this movement sends signals to the brain about the position of your head. Your brain uses this information to help your body stay balanced.
Damage to the vestibular system caused by disease or injury can severely affect a person's balance. Consuming too much alcohol can also temporarily affect the vestibular system. Because alcohol thins the blood, it also changes the viscosity of the endolymph. The thinned-out endolymph sends signals to your brain that your body is rotating even though it is not. This is why many people feel like the room is spinning when they are drunk.
According to the text, which of these is true regarding the semicircular canals?

A) They excrete a fluid called endolymph.
B) At rest, they send information to the brain.
C) They are able to perceive a range of movements.
D) They contain fluid that is constantly in motion to maintain balance.