Of the following, which is an example of a mutualistic relationship? (A) the protozoan Trichonympha digesting wood in the gut of a termite (B) the sporozoan Plasmodium reproducing in human blood cells and liberating toxins into the human body (C) two species of Paramecium deriving food from a common laboratory culture (D) rabbits being eaten by foxes (E) humans inadvertently providing food for cockroaches unanswered

(A) option is correct

Explanation:

The protozoan Trichonympha digesting wood in the gut of a termite is the classic example of a mutualistic relationship

Trichonympha is an endosymbiont that live inside the intestine of termite whereas termite live on cellulose mostly from the dead wood they chewWithin the termite's digestive enzyme Trichonympha provides enzymes which can breakdown the woodTrichonympha manufacture the enzyme cellulase, which breaks the chemical bonds in cellulose and then the termites can eat woodIn return termite provides shelter to Trichonympha inside its gutThe sporozoan Plasmodium reproducing in human blood cells and liberating toxins into the human body is an example of parasitism where Plasmodium is benefited because it is reproducing inside human body whereas human body is getting toxicTwo species of Paramecium deriving food from a common laboratory culture is an example of competition because both are competing for the same food sourceRabbits being eaten by foxes is an example of predation because here rabbit is acting as a prey whereas fox is a predatorHumans inadvertently providing food for cockroaches is an example of commensalism because here cockroaches are being benefited from humans but humans are neither benefited  nor harmed

The answer would be sand and gravel