Organisms that cannot make their own food and must obtain energy from external sources are called
a. autotrophs.
b. heterotrophs.
c. thylakoids.
d. plants.

Heterotrophs

Explanation:

Organism that cannot make their own food and depends on the external sources for its energy are known as the heterotrophs.

They are dependent on the other organisms for their energy. They feed on the plants or animals for their energy.

Other than plants all the other organisms are dependent on food from other sources as they lack the ability to make food by their own.

the sun d the answer is sun

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