Question

the original source of energy for the pyramid is the
a sun.
b all photosynthetic organisms.
c decomposers, not seen in the pyramid.
d phytoplankton, which are photosynthetic.

Explanation:

The pyramid shows a food chain starting with phytoplankton (producers). Producers like phytoplankton get energy from the Sun via photosynthesis. Thus, the original energy source is the Sun.

Answer:

A. Sun.