Inverted pyramid is found in

The pyramid of number is based on

In an ecological pyramid,what does the base represent?

Given below is the diagram of an ecological pyramid. This type represents:

Consider the following statements about ecological pyramids:
$I.$ Charles Elton developed the concept of ecological pyramid.
$II.$ After his name,these pyramids are also called as Eltonian pyramids.
$III.$ It is a graphical representation or pyramid-shaped diagram which depicts the number of organisms,biomass,and energy at each trophic level.
Which of the statements given above are correct?

Assertion : In a food chain, members of successive higher levels are fewer in number.
Reason : Number of organisms at any trophic level depends upon the availability of organisms which serve as food at the lower level.