Question

the endosymbiotic theory helps to explain the origin of which structures?
○ mitochondria
○ ribosomes
○ nuclei
○ cell membranes

Explanation:

The endosymbiotic theory proposes that mitochondria (and chloroplasts) originated from prokaryotic organisms that were engulfed by a host cell. Ribosomes, nuclei, and cell membranes have different evolutionary origins not explained by this theory.

Answer:

A. mitochondria