Correct Option (1)
The given number pattern follows a specific arithmetic rule applied column-wise. For each column, the element in the fourth row is determined by the elements in the first, second, and third rows.
The established rule is: (First Row Element) + (Third Row Element) - (Second Row Element) = (Fourth Row Element).
Applying this rule to the existing columns:
- Column 1: 8 + 4 - 6 = 6
- Column 2: 10 + 6 - 5 = 11
- Column 3: 15 + 8 - 7 = 16
Applying the same rule to the fourth column to determine the missing number (?):
- Column 4: 13 + 8 - 4 = 17
Therefore, the number at (?) is 17.
Incorrect Options:
Options 2 (19), 3 (21), and 4 (23) are incorrect. These values do not conform to the established column-wise arithmetic pattern, which consistently applies the operation: (First Row Element) + (Third Row Element) - (Second Row Element) = (Fourth Row Element).