B.A and M.A

Banta Singh : "Yaar Santa, last year the name-plate outside your house read Santa Singh, B.A. This year it reads Santa Singh, M.A.When did you finish your Masters Degree?"
Santa Singh: "You don't understand. Last year my wife died , I put B.A. to indicate Bachelor Again. Then I took a second wife, So M.A . is Married Again ."