Look at the code below. You have four classes (O, X, T, and M) and a variable of each of...

Look at the code below. You have four classes (O, X, T, and M) and a variable of each of these.

O o;

X x;

T t;

M m;

The following assignments are all legal (assume that they all compile):

m = t;

m = x;

o = t;

The following assignments are all illegal (they cause compiler errors):

o = m;

o = x;

x = o;

What can you say about the relationships of these classes? Draw a class diagram.