Which of the choices below describes the pathway of cellular respiration (the complete oxidation of glucose)?

A. Intrinsic salivary gland: This is a general category, not a pair of specific glands, so it doesn't answer the two-part question.
B. Lingual; labial: Both lingual and labial glands are intrinsic (minor) salivary glands.
C. Submandibular; lingual: The submandibular gland is one of the major extrinsic salivary glands, while lingual glands are minor intrinsic glands located in the tongue.
D. Submandibular; sublingual: Both are extrinsic salivary glands.
E. Sublingual; parotid: Both are extrinsic glands; the parotid is the largest.
F. Lingual; sublingual: Lingual is intrinsic; sublingual is extrinsic, so the order here is reversed.

A. Potassium ion concentration in extracellular fluid: High levels of extracellular potassium stimulate aldosterone secretion and enhance potassium secretion into the renal tubules for excretion. This is the most direct and critical factor.
B. Intracellular sodium levels: While sodium levels affect membrane potentials, they do not directly regulate potassium secretion.
C. The pH of the intracellular fluid: pH changes can influence potassium distribution between compartments but are not the main driver of secretion.
D. The potassium ion content in the renal tubule cells: This reflects storage, not the signal for secretion. The extracellular fluid concentration is what regulates the process.