Which statement correctly describes negative, equilibrium, and positive nitrogen balance?

• A. Negative: only occurs during pregnancy; Equilibrium: only occurs in athletes; Positive: only occurs during starvation
• B. Negative: intake > excretion (growth); Equilibrium: intake < excretion (wasting); Positive: intake = excretion (steady state)
• C. Negative: intake = excretion; Equilibrium: intake > excretion; Positive: intake < excretion
• D. Negative: intake < excretion (protein loss); Equilibrium: intake = excretion (maintenance); Positive: intake > excretion (net protein gain)

Answer: (D)