Unlike animal-like protists, many fungus-like protists are a) decomposers b) parasites c) heterotrophic d) unicellular

a) decomposers i think im not 100% sure.

A. decomposers

The decomposers are organisms that break down the dead and decaying organisms such as plants and animals. The fungi are the primary decomposers if the litter in the ecosystem. The fungi are saprophytic organisms which feed upon the nutrients obtained after the decomposition process. They exhibit a fungal hyphae which can penetrate deep inside of soil in order to obtain the food. Protists are simple unicellular organisms, these are members of the kingdom Protista. Some of these Protists shows similarity in structure and function with animals, plants, fungi and microbes. The molds are protists which are found on feeding upon dead decaying matter like fungi. Examples are slime mold and water molds.

b.have there own function.

i think that is new experiments yield untrustworthy data and should be carefully considered, because you don't know what will happen with the experiments.