Organisms at the bottom of the pyramid produce enough usable chemical energy to support the entire ecosystem through
a) predation.
b) photosynthesis.
c) cell respiration.
d) anaerobic respiration.

The correct answer is -

B) photosynthesis

Explanation:

Photosynthesis can be described as process of creating food (in the form of glucose) in green plants, algae, and some protist (that are called producers). It uses inorganic molecules that are carbon dioxide and water in the presence of energy from sunlight to synthesise glucose and release oxygen as waste in surroundings.

It takes place in the specialized membrane bound organelles, called chloroplast.

Producers occupy the base of any food chain, which can be represented by energy pyramid, thus they produce enough chemical energy to support the entire ecosystem through photosynthesis.

humans can cause extinction of a species through overharvesting, pollution, habitat destruction, introduction of invasive species (such as new predators and food competitors), overhunting, and other influences. explosive, unsustainable human population growth is an essential cause of the extinction crisis.

explanation:

i didn't have the answer choices , but i tried my best.

if you know your abc's you should be able to get your answer or just use google