Which travels at the greatest speed?
a. sound through air
b. light through glass
c. sound through water
d. light through a vaccum.
i think it's between a. and d. but i'm not sure. me

"Light through a vacuum" is the one among the following choices given in the question that shows which can travel at the greatest speed. The correct option among all the options that are given in the question is the fourth option or option "D". I hope that this is the answer that has come to your desired help.

As newton's first law states a object in motion stays in motion