How much ATP can oxidation of a 16-carbon atom fatty acid yield?

A. Intracellular fluid: Intracellular fluid is inside the cells. Edema refers to fluid accumulation outside the cells, so this is incorrect.
B. Interstitial fluid: Edema is caused by the abnormal accumulation of fluid in the interstitial space, which is the space between cells in tissues.
C. Intracellular fluid and interstitial fluid: Edema is confined to the interstitial (extracellular) compartment, not intracellular.
D. Blood plasma: Although fluid may move from the plasma into the interstitial space, edema refers to fluid retention in tissues, not in the blood plasma.

A. Because it saves one step in its synthesis: Zymogen secretion is about preventing premature activation, not simplifying synthesis.
B. So it will start digesting intracellular proteins of the chief cells more quickly: This would be harmful-zymogens prevent self-digestion of the cells that produce them.
C. So it acts only in the stomach lumen and does not digest intracellular proteins: Pepsin is secreted as inactive pepsinogen to prevent it from digesting the proteins inside chief cells. It is only activated to pepsin in the acidic environment of the stomach lumen.
D. So it can start digesting dietary proteins more quickly: Speed is not the reason for secreting it as a zymogen-safety is.