A facultative parasite refers to a species, which may resort to parasitic activity, but is not completely dependent on any host for finishing its life cycle. Therefore, the growth of Armillaria fungi inside a tree's roots, making the tree to rot, but will survive even if the tree dies, is an example of facultative parasitism.
An obligate parasite refers to a parasitic species, which cannot finish its life-cycle in the absence of a suitable host. Therefore, rickettsia bacteria's tendency to surviving only in a eukaryotic cell is an example of obligate parasitism.
A long-term symbiosis or biological association in which members of one species attain benefits while those of the other species is neither harmed nor are benefited is known as commensalism. Hence, a pseudoscorpion, a kind of arthropod hiding under the wings of beetle for protection and transportation, however, it does not affect the beetle is an example of commensalism.
Predation refers to a biological association, where one species, the predator, kills and consumes another species, known as prey. A freshwater amoeba feeds on bacteria in the water is an example of predator and prey.
D. They contain many carbon atoms
The first options answer is phloem while the second answer is roots
