Question

what event allowed complex eukaryotic cells to evolve from simpler prokaryotic cells?
enlarged polar heads passing on traits
infolding an organelle forming lysosomes

Explanation:

The endosymbiotic theory suggests that eukaryotic cells evolved from prokaryotic cells through processes like infolding of cell membranes to form organelles. Enlarged polar heads relate to lipid bilayers, passing on traits is general heredity, and forming lysosomes is a later cellular function. Infolding an organelle (like the nuclear envelope from plasma membrane infolding) is key in eukaryotic evolution.

Answer:

infolding an organelle