The roots of many clover plants produce structures that are filled with bacteria. The clover plants provide food and shelter for the bacteria, while the bacteria produce a nutrient that is used by the plants. As a result, clover plants that have these structures on their roots grow at a faster rate and are healthier than clover plants that do not have the structures. What type of relationship exists between the clover plants that have these structures on their roots and the bacteria in the structures?
	A		mutualism

	B		parasite-host

	C		predator-prey

	D		commensalism