im sorry to say but you are incorrect my Lil amigo, if you look at the chart there are 4 layers, layer 4 is the further beneath the ground then 1,2 and 3, so there for y,u are the longest to live, layer 1 is the shortest BC it is basichly on the crust of the earth so there for the answer is (C. organism Y and organism U were alive over the same time span .
i hope i helped you have an amazing day) :) <3