Which of the following is thought to be engulfed by prokaryotes eventually leading to the development of animal cells? A. mitochondria B. chloroplasts C. aerobic bacteria D. cyanobacteria

Mitochondria are thought to have been engulfed by prokaryotes, resulting in the development of animal cells. This hypothesis is supported by the mitochondria's ability to create energy for themselves using food and the fact that mitochondria have their own DNA, known as mitochondrial DNA.