Let the front row have \(a\) children. The rows then have \(a, a-3, a-6, \dots\) children (an AP with difference −3).

Total for \(n\) rows: \(na - \frac{3n(n-1)}{2} = 260\)

\(a\) must be a positive whole number. Check each option:

• \(n = 3\): \(3a - 9 = 260\), \(a = 89.67\). Not possible.
• \(n = 4\): \(4a - 18 = 260\), \(a = 69.5\). Not possible.
• \(n = 5\): \(5a - 30 = 260\), \(a = 58\). Works (rows of 58, 55, 52, 49, 46).
• \(n = 6\): \(6a - 45 = 260\), \(a = 50.83\). Not possible.

Answer: (C) 5