The endosymbiotic theory to explain the origin of which structures?
mitochondria
ribosomes
nuclei
cell membranes
prokaryotic and eukaryotic cells
aye need here

The right answer is Mitochondria.

In the 20th century, scientists thought that plastids and mitochondria could come from procaryotes (bacteria). These would have been ingested by cells and live within them (in symbiosis). This endosymbiotic theory became perfectly plausible when it was discovered (in the 1950s and 1960s) that these organelles contained theori own DNA, tRNA and rRNA.

Answer : The correct answer is -

mitochondria.

Endosymbiotic theory is an evolutionary theory that describes the origin/evolution of eukaryotic structures, chloroplast and mitochondria from prokaryotic organisms. According to this theory, some bacteria (prokaryotic cell) were considered to live inside larger cells (that is in a symbiotic association). Later those bacteria became the part of larger cells and thought to evolve i to mitochondria and chloroplast, which are now the subcellular structures of eukaryotes.

Thus, mitochondria is the right answer for the question.

it is a. i hope this .