To prove that a set X does not equal a set Y $,$ you need to find an element that is in $\_\_\_\_\_$ and not $\_\_\_\_\_$ or that is in $\_\_\_\_\_$ and not $\_\_\_\_\_.$

fill the blanks from the options below

Question $7$Select one:

a$.$

all answers are wrong.

b$.$

X; in Y ; Y ; in X

c$.$

Z; in X ; X ; in Z

d$.$

X; in X ; Y ; in Y