Is it believed mitochondria evolved from cyanobacteria or aerobic bacteria?

The answer of this question us Cyanobacteria .

Explanation:

Mitochondria have different type of organelles in the cell , mitochondria evolved in cynaobacteria . Cynobacteria also known as Cyanophyta a phylum of bacteria ,Cynobacteria found in fresh water in terrestrial environment. Cynobacteria are thought to have converted the early oxygen poor,decrease atmosphere .Cynobacteria which  are prokaryotes are called blue green algae.  Blue green algae contain different photosynthetic pigment example red, pink color pigments. Example are Spirulina. Cynabacteria are one of the few micro-organisms that convert inert atmospheric nitrogen into a usable form, such as ammonia or nitrate. For example, the cyanobacteria Anabaena co-exist with a type of fern called Azolla, where it supplies nitrogen to the plant.