[问答题]
The following diagram shows a trophic ld pqc8 2dz n41n;yymd.evem)iw +g,cm;;xr e ln4m/ v/dvtl pyramid of energy.
1.Label the bottom (step A) and topmost steps (step D) of the pyramid to describe what types of organisms are present in the two levels.
2.State which trophic level can support the largest population of people, step A or step B?
3.Explain why animals at level D are most vulnerable to becoming extinct.
