That would be a Chloroplast
The answer is the last one: amoebas, yeasts, hydras, and ferns
Your answer would be C: Arachnids
He could race multiple cars with different weight added on them and do multiple races (just to be sure) and see if his theory was correct, if not he should right down what he has learned from his experience! :D
-You'll never learn if u don't try ;)
