Correct option is: C) 72°
Given that
sin \(18^\circ\) = cos x
= sin \(18^\circ\) = sin (\(90^\circ\) - x) (\(\because\) sin (\(90^\circ\) - \(\theta\)) = cos \(\theta\))
= \(18^\circ\) = \(90^\circ\) - x
= x = \(90^\circ\) - \(18^\circ\) = \(72^\circ\)