hello, the attachment is the question and answer, in regards to part d, im confused with the question "U takes the minumum of X and Y" What does that...

hello,

 the attachment is the question and answer, in regards to part d, im confused with the question "U takes the minumum of X and Y" What does that mean, the minimal of the product of X and Y or the minimal probability of X and Y. Also im confused how the answer subsititued U to Y