Which of the following is the probability distribution, px(x)?

The top one
because if we have RR RB BR BB then blue occurs 4 times in total. 1/4 blue occurs 0 times, 2/4 blue occurs once and 1/4 times blue occurs twice therefore if we write these as a decimal 0 blue - 1/4 - 0.25
1 blue - 2/4 - 0.5
2 blue - 1/4 - 0.25