Which one of these facts about mitochondria and chloroplasts constitutes support for the endosymbiotic theory?
a. their dna resembles bacterial rna.
b. their ribosomes resemble the ribosomes of bacteria.
c. they are organelles that are found within plant cells.
d. they reproduce by mitosis.

The correct answer will be option B (Their ribosomes resemble the ribosomes of bacteria).

Explanation:

Endosymbiotic theory was proposed by Biologist Lynn Margulis in the 1960's which stated that a large cell ingested the bacteria for survival which became dependent on one another, resulting in a permanent relationship which cannot live outside the cell.

Mitochondria and chloroplasts were evolved from the endocytosis of prokaryotes aerobic and photosynthetic bacteria respectively.

Both mitochondria and chloroplasts posses their own DNA and 70S ribosomes which shows similarity to the DNA and ribosomes of bacteria.

Thus, option B is the correct answer.

the oldest known insects are believed to live around 400 millions ago as suggested by the fossil records.   some plants having woody stems also evolved during this time.

after the evolution of insects the first four legged species or the tetrapods evolved in shallow freshwater habitats from the intermediate species approximately 397 million years ago. the tetrapods went on conquering the land giving rise to amphibians, reptiles, mammals and birds.

the major split in tetrapods first occurred 340 million years ago branching off from amphibians.

363 million years ago when the carboniferous period began the insects started roaming on land and taking flights, following which the four limbed tetrapods adapted in the terrestrial habitat.

"it built up in the atmosphere"

i think thats it, idk, i tried looking for this exact q& a for grad. and idk if i got this question right or sorry if im wrong