Check all statements that are always true for any predicate ( p ) on any (nonempty) domain of two variables, and only those statements.
a) ( p(x, y) ) is true for some values of ( x ) and ( y ).
b) ( p(x, y) ) is false for all values of ( x ) and ( y ).
c) ( p(x, y) ) is true for all values of ( x ) and ( y ).
d) ( p(x, y) ) is false for some values of ( x ) and ( y ).
