The metabolic type of nitrifying bacteria is autotrophic aerobic. Autotrophic is divided into photoautotrophic and chemical autotrophic. It is an autotroph of nitrifying bacteria. The definition of chemoautotrophy is that organisms can assimilate inorganic matter (CO2) into their own nutrients (i.e. organic matter). For chemoautotrophic organisms, their energy substances come from the oxidation of H2S (sulfide bacteria), NH3 (nitrifying bacteria), ferrous (iron bacteria) and so on. For nitrifying bacteria, it is to oxidize NH3 to obtain energy.

Lactic acid bacteria are usually used for lactic acid fermentation, and electron acceptor is an intermediate metabolite whose substrate is not completely oxidized. So it is anaerobic, because organic fermentation needs energy, but lactic acid is produced by sugar fermentation, not by decomposing lactic acid.

Rhizobia are heterotrophic aerobic rhizobia, which need to infect plants to form nodules to help nitrogen fixation and provide nitrogen sources for plants, while plants provide their own growth energy for rhizobia, forming a mutually beneficial relationship. Rhizobia is an aerobic nodule, and its oxygen concentration is controlled by leguminous hemoglobin, which can not only maintain the growth of nodules, but also control the oxygen concentration from being too high. Because the nitrogenase of rhizobia is inactive under aerobic conditions, it must be in a micro-aerobic environment.

Chlamydomonas is also called Chlamydomonas. Chlorophyta, Chlamydomonas. Algae are single-celled, spherical or elliptical, with two flagella of equal length at the front end, which can swim. Chlamydomonas belongs to both plants and unicellular organisms. It is a eukaryote and a microorganism. It likes light and needs oxygen. Autotrophic aerobic

To sum up, C and D are right.

I wonder if you made a mistake. We have an original question about microbiology and fermentation engineering, in which the metabolic type of rhizobia is autotrophic aerobic, which is wrong.