Answer:
Symbiosis is a close relationship between two species in which at least one species benefits. Mutualism is a symbiotic relationship in which both species benefit. Commensalism is a symbiotic relationship in which one species benefits while the other species is not affected.
The healing of a wound in a human is most similar to the process of regeneration, I believe.
The correct option is D. Organisms work best at their optimum temperature and pH, above and below these temperature they will not be able to function as expected. It is possible that the students above use different temperature and pH when they were carrying out their experiments, this will result in different efficiency rate by the yeasts.