Fact 1: Organs of excretion make up the excretory system. Fact 2: Excretion begins with the kidneys. Given the two facts above, kidneys are a part of what system?
Options:
a). allow growth.
b). excretory.
c). respiratory.
d). organ.
e). complex.
f). storing water.
g). endocrine.
h). circulatory.
b).