If X is mortal, Y is wise, if Z is not good, a will suffer. Y is not wise, if A suffers. If B is slave, X is immortal. If A suffers, what follows?

If X is mortal, Y is wise, if Z is not good, a will  suffer.   Y is not wise, if A suffers.  If B is slave, X is  immortal.   If A suffers, what follows?
(a) X is mortal
(b) B is a slave
(c) Z is good
(d) Y is wise

Answer: B is a slave