<span>The different adrenal hormones show selectivity for different types of adrenergic receptors. This may be because the chemical structures of the adrenal hormones are such that binding is biochemically easier for the hormones at the receptors to which they show a selective affinity.</span>
i think it's the independent variable
16) B. chains of rods
18) C. water
15) C. facilitated diffusion
5) C. mitochondria contain their own ribosomes