Why are there less organisms as you move up the pyramid?

As we go further along a food chain, there are fewer and fewer consumers. The further along the chain you go, the less food (and hence energy) remains available. In other words, a large mass of living things at the base is required to support a few at the top

russia because it is the biggest state

the answer should be a. the sui empire, the tang empire extended from korea in the west to manchuria in the east.