Which statement best describes how biologists think eukaryotic cells evolved
from prokaryotic cells?
A. Pockets of DNA covered by membranes had mutations that made
them eukaryotic.
B. Small cells were engulfed by larger cells and became organelles
through endosymbiosis.
C. Small predatory cells invaded and took over larger cells that
needed help to survive.
D. Competition for resources in the ocean caused some cells to
develop organelles.