Question 7 which of these has the greatest mobility? the unicellular euglena the slime molds the mat-forming algae all have the same mobility

I believe the answer is Unicellular Euglena. 
Euglena are unicellular organisms classified into the kingdom protista, and the phylum euglenophyta. All euglena have chloroplast and can make their own food by photosynthesis. They are considered to have both plant and animal features. The mobility of Euglena also allows for hunting capability, because of this adaptation. 

I'm pretty sure it is b. protist