Prokaryotes that harvest both energy and carbon atoms from organic molecules are called?
a. chemoautotrophs
b. chemoheterotrophs
c. photoautotrophs
d. photoheterotrophs
e. nitrogen fixers

B. Chemoheterotrophs

Explanation:

Photoheterotrophic organisms obtain energy from light and carbon from organic molecules, while photoautotrophs obtain both carbon and energy from light.

Nitrogen fixers, as they name states, need nitrogen to synthesize other molecules, such as proteins and amino acids.

While chemoheterotrophic organisms are those who cannot obtain their energy and carbon from light, but instead they obtain their organic molecules by feeding on other -either alive or dead- organisms. Therefore, they obtain both energy and carbon atoms from organic molecules.