WHY IS DIFFUSION INSUFFICIENT TO MEET THE OXYGEN RECQUIREMENT OF MULTICELLULAR ORGANISMS LIKE US?

2 answers

that question would have been much more easier to read it it wasn't it capitalization.
Think of the organisms that use diffusion for gas exchange. Most of them have a very high surface area to mass ratio.

I'll give you a big hint, there's a relationship between speed of diffusion and the distance over which something is being diffused.