Two friends are about to try a new obstacle course. Neither of them has seen the course before, so the first one to go through is at a disadvantage. For this reason, the friends must have a fair way to pick who goes first. Which probability model gives each friend an equal chance of being selected to go through the course first? A
The friends take turns selecting a card from a deck of 52 cards without replacing it. The first friend to pick a king goes first.

B
The friends have three straws and cut one so it is shorter than the other two. The friends take turns randomly selecting a straw without replacing it. The friend who picks the short straw goes first.

C
The friends put 4 marbles in a bag: 3 are red and 1 is blue. The friends take turns drawing marbles. The first friend to pick a red marble goes first.

D
One friend writes 1 and 2 on two slips of paper. The other friend randomly picks a slip of paper. The friend who picks a 1 goes first.