Mr.A has x children while Mrs.B has (x+1) children. After they got married, totally they have 10 children. But it is not given how many children do they have after they got married. Let they be 'y'. Then, we get,
x+(x+1)+y=10 i.e. 2x+y=9. Here, if y can take only odd values, otherwise, x will not be a positive integer for any even value of y.
Then there are following cases:
1) for y=1, x=4 and x+1=5,
2) for y=3, x=3 and x+1=4
3) for y=5, x=2 and x+1=3
4) for y=7, x=1 and x+1=2
5) for y=9, x=0 and x+1=1.
As the children of same parents cannot quarrel, only y can quarrel with x and (x+1) and x can quarrel with (x+1). Then from above five cases, we have to consider the case which will give maximum value. It is the the 2nd case. That is, the product xy+y(x+1)+x(x+1) will be maximum for y=3, x=3 and (x+1)=4, that is 33.
Hence 33 is the answer.
OPTION A 33