1I alone is sufficient while II alone is not sufficient
2II alone is sufficient while I alone is not sufficient
3Either I or II is sufficient
4Neither I nor II is sufficient
Since 8th to the left of 12th from the right is 20th from the right, so from I, we know that Vishakha is 5th from left and 20th from right i.e. there are 4 children to the left and 19 to the right of Vishakha. So, there are (4 + 1 + 19) i.e. 24 children in the row.
From II, Nisha is 7th from right and 18th from left end of the row.
So, there are (6 + 1 + 17) = 24 children in the row.