Answer:
Sexually reproducing
Step-by-step explanation:
Sexual reproduction increases genetic diversity whereas, asexual reproduction does not contribute towards genetic diversity.
So suppose a bacteria comes and brings a disease, well the protists that are asexually reproducing are parental copies (same DNA as parent) so if parent dies to the disease then you know they will die too.
Whereas, for sexually reproducing protists, genetic diversity comes into play because sexual reproduction basically use DNA of both parents and make unique kid so this unique kid has better chance of surviving the disease even if his parents fall to it.