Well all cells in a multicellular organism have the same exact DNA (except for sex cells). But what makes each type of cell different physically and functionally is the genes that are expressed in those cells.So for like example a different section of the DNA molecule is expressed in a nerve cell than a skin cell.
It's the 4 the answer I hope it has served you
They are able to travel in a vacuum at the same speed.
Hope it helps
Not enough ..................
