Why is it an advantage for some plant like protists to be able to move using a flagella

Last week i was assigned a thematic. we have groups of three but the people i was assigned with haven't been in school for days. i would appreciate if anyone can me with my thematic . i highlighted most of the important steps and i circled my thematic topic. in desperate need : ( its due on february 19

The rapid decomposition of organic matter produces evidence which supports: the slow accumulation of coal deposits long ages of the earth rapid burial of vast amounts of vegetation biblical account of noah's flood

Idon’t know the answer and i’ve been stuck on it for a while now skskskskks