The name of a bacterium which derives its energy from oxidizing nitrites into nitrates is...

Explanation

This question is asking for the name of a bacterium that gets its energy from converting nitrites into nitrates. Nitrites and nitrates are both forms of nitrogen, which is an important element for living organisms. Bacteria play a vital role in the nitrogen cycle by converting different forms of nitrogen into usable forms for plants and other organisms. The correct answer to this question is option C: Nitrobacter. Nitrobacter is a type of bacteria that is involved in the process of nitrification, which is the conversion of ammonia and nitrites into nitrates. Nitrates are an important source of nitrogen for plants, which use them to synthesize proteins and other essential molecules. Nitrosomonas, option A, is also a type of bacteria involved in the nitrogen cycle, but it converts ammonia into nitrites instead of oxidizing nitrites into nitrates. Azotobacter, option B, is a type of bacteria that is capable of fixing nitrogen from the atmosphere into a usable form for plants. Escherichia coli, option D, is a type of bacteria that is commonly found in the intestines of humans and animals and is not directly involved in the nitrogen cycle. Understanding the roles of different types of bacteria in the nitrogen cycle is important for understanding how nitrogen moves through ecosystems and how it is made available to different organisms. For more information, please see the relevant sections of your recommended Biology textbooks.