Which component of blood is responsible for transporting oxygen to tissues?

A. Non-steroid hormones include lipid-based molecules.:Many non-steroid hormones are peptide- or amino-acid–derived and are water-soluble rather than lipid-based, although some non-steroid hormones (like thyroid hormones) are lipid-soluble exceptions.
B. Non-steroid hormones contain fatty acids.:Non-steroid hormones are typically peptides or amino-acid derivatives and do not characteristically contain fatty-acid structures.
C. Steroid hormones are derived from cholesterol.:Steroid hormones are synthesized from cholesterol, giving them a four-ring lipid structure that makes them lipid-soluble and able to cross cell membranes.
D. Steroid hormones are composed of amino acids.:Steroid hormones are not composed of amino acids; amino-acid composition is a feature of peptide hormones and some amine hormones.

A. By altering the pH of the blood.:The nervous system does not regulate endocrine responses by changing blood pH as a primary mechanism.
B. By increasing blood flow to endocrine organs.:While blood flow can influence hormone delivery, direct neural control of endocrine responses is primarily mediated via hypothalamic signaling rather than blood-flow changes.
C. By releasing hormones that regulate the pituitary gland.:The hypothalamus (a neural structure) secretes releasing and inhibiting hormones that regulate anterior pituitary secretion and sends neural signals to the posterior pituitary.
D. By directly stimulating adrenal cortex hormone release.:Direct neural stimulation primarily affects the adrenal medulla (catecholamine release); adrenal cortex activation is mostly hormonal via ACTH from the pituitary.