To celebrate her upcoming graduation Keysi books a trip on a space party-boat that travels at 99% the speed of light. She tells her mom she'll be "right back" and goes for a 3 day trip around the solar system. If the clocks on her space ship read 3 days, how many days does her mom wait for her to return? *
5 days
9 days
12 days
15 days
21 days
25 days