What was the relation between Umar and Ali?

(A) Umar (R.A) was father-in-law of Ali (R.A)
(B) Ali (R.A) was father-in-law of Umar (R.A)
(C) Brothers
(D) Cousins

The answer is: (B) Ali (R.A) was father-in-law of Umar (R.A)