Afigure of speech which explicitly compares two different things using the words "like or as", sometimes referred to as approximations?

explanation: the line "to save the day, harry must get past a scary three-headed guard dog" from the summary best justifies the conclusion that harry potter and the sorcerer’s stone was influenced by ancient greek mythological literature. the three other choices had nothing to do with ancient greek literature - and the words "three-headed guard dog" are what makes that choice the correct answer.

lab rats that ate more artifical sweeter gained more weight than those who ate sugar and they had “lower levels of a hormone called glp-1, which affects how full we feel.”