In the following question, a matrix of certain characters is given. These characters follow a certain trend, row-wise or column-wise. Find out this trend and choose the missing character accordingly.
3 6 8
5 8 4
4 7 ?

Answer: A. 6

Clearly, sum of numbers in each row is 17.
So, missing number = 17 - ( 4 + 7 ) = 6.