[单选题]
3. Which of the following decrease ap .c:cs)uq l9mt the stage in the food :d vqxmg2s 9.lchain from producer to primar:m9qxgl. s2d vy consumer?
I. Population.
II. Biomass.
III. Chemical energy.
IV. Heat energy
A. I and II only
B. II and IV only
C. II and III only
D. I, II and III only