What is one major factor that affects the health of coral reefs

Option C .

Explanation:

Phylum platyhelminthes are flat worms. They have soft, unsegmented body. They are aceolomate I.e. lack body cavity. Flatworms are bilaterally symmetrical and are tripoblastic I.e they have three germ layers. Flatworms are mostly parasitic with few free living.

Their body is dorsal ventrally flattened. They are hermaphrodites I.e they have both male and female sexual organs and can reproduce sexually and asexually.