Final answer:
Option A is the best retelling, accurately describing sloths' slow movement, algae-covered fur, and potential cancer-fighting fungi. It avoids subjective descriptions yet emphasizes sloths' ecological roles and adaptive behaviors in their habitat.
Step-by-step explanation:
Among the given retellings, option A provides the most accurate summary of a passage about sloths. This retelling commits to facts by mentioning that sloths move slowly as a protective mechanism, and that algae grows on their fur, which can be consumed by other animals like birds. Furthermore, it correctly asserts that the fungi which may be found within this algae has the potential to fight cancer.
However, it is important to note that being 'helpful' is a subjective term, and while sloths do contribute to their ecosystem, they do so not out of intention to be 'helpful' but as a part of the natural symbiotic relationships that exist in their environment.
It is also essential to understand that while sloths are indeed good swimmers and spend much of their time in trees in tropical areas of South America, the retelling should avoid anthropomorphizing sloths by describing them as 'helpful' in human terms, as their behaviors are instinctive survival adaptations rather than conscious actions.