The golf-ball sized structure found inferior to the urinary bladder, and surrounding the most proximal portion of the urethra, is called the

A. Lymph nodes: Lymph nodes do undergo some changes with age but not as dramatically as the thymus.

B. Thymus: The thymus undergoes involution after puberty, shrinking in size and being replaced largely by fat, which significantly reduces T-cell production.

C. Spleen: While some function may decline with age, the spleen does not undergo the same marked involution as the thymus.

D. Pharyngeal tonsils: The tonsils may atrophy slightly with age, but the effect is less pronounced than with the thymus.

E. Appendix: The appendix may reduce in lymphoid tissue over time but does not exhibit the same profound involution.

A. Proteins and carbohydrates; fats: Both proteins and carbohydrates yield approximately 4 kcal/g, while fats yield about 9 kcal/g due to their dense hydrocarbon structure.
B. Proteins; fats and carbohydrates: Carbohydrates do not yield 9 kcal/g; only fats do.
C. Fats; carbohydrates and proteins: Fats yield more energy, not less.
D. Carbohydrates; fats and proteins: Proteins and carbohydrates are equal in kcal/g; fats are higher.
E. Carbohydrates and fats; proteins: Fats yield the highest kcal/g, not proteins.