I will now show that matrix X is the scrambled version of Z. We know from lectures that 2 graphs have the same degree sequence if and only if one is a two switch of the other [Theorem 1.7 (Berge)]. Then if we sum up the columns/rows of the adjacency matrix to get the degrees of each vertex, then sort them in descending order, we have the degree sequence of the graph corresponding to the adjacency matrix. I computed the degree sequence of X, Y and Z in MATLAB and it was clear that X and Z had matching degree sequence and Y's degree sequence did not match(see code below). This shows that X is the scrambled bipartite graph.
In conclusion by elimination Y is the Erdos-Renyi Type I random
graph, Z is the bipartite graph and X is the scrambled version of Z.
MATLAB code for Q2.