When someone stands with their knees locked, they may feel dizzy, nauseous, and possibly faint due to a drop in blood pressure. this resulting drop in blood pressure would be classified as the
a
stimulus
b
sensor
c
control center
d
effector

the correct answer: the index of refraction of the second medium is lower i tried this persons answer and it was wrong this person is lying

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.