Certain types of have a relationship with certain plants where they convert nitrogen into a usable form.
a. fungi b. animals c. bacteria d. viruses

Answer is C. Bacteria

Certain types of bacteria have a relationship with certain plants where they help convert nitrogen into a usable form.

Explanation:

Nitrogen is abundant in the atmosphere, but plants cannot use it because of the absence of a necessary enzyme, nitrogenase, which converts nitrogen into a usable form.  So they form a symbiotic relationship (mutually-beneficial arrangement) with nitrogen fixing soil bacteria (rhizobia) which perform biological nitrogen fixation. Biological nitrogen fixation is a process in which the symbiotic nitrogen-fixing bacteria coverts atmospheric nitrogen into ammonia and organic derivatives that plants can use to synthesize proteins.  This bacteria form nodules on the roots of plants like legumes in which nitrogen fixation takes place.

Both plants and bacteria benefit from this symbiotic relationship, as the plant obtains ammonia to synthesize proteins from nitrogen in the atmosphere while bacteria obtain carbon compounds from the plant produced through photosynthesis and a secure environment to grow. As the plant roots leave behind some of the usable form of nitrogen in the soil, this process also increase soil fertility.

only about ten percent of the energy at one trophic level is passed on to organisms at the next trophic level. the remainder of the energy is used in life processes or lost as heat.