Why do astronomers use astronomical units (AU) instead of kilometers (km)?(1 point) AU is used in astronomy, while km is used in physics.
There are no km in outer space, only AU.
Large distances are easier to express in AU than in km.
AU is used for spacing, while km is used for length.

Epinephrine is a hormone released from the adrenal gland of the body, most often in a stressful situation. it is known as the "fight-or-flight" hormone. one way that it causes a response in the body is to activate receptors on muscle cells. where are these cellular receptors located? a. on the cell membrane b. in the nucleus c. on the cell wall d. around the mitochondria

Long term exposure to waves can cause sunburns and skin cancer.

When listening the levels of orginization in orginisims from the smallest to most complex , which level is just below organs in complexity