Since \(A\) repel \(B\),\(A\) and \(B\) have same nature of charge.
And as \(A\) attracts \(C,A\) and \(C\) have opposite nature of charge.
Hence,\(B\) and \(C\) also has opposite nature of charge. And, hence nature of force between \(B\) and \(C\) will be attractive.
$\left[ g =9.8 \,m / s ^{2}, \sin 30^{\circ}=\frac{1}{2}\right.$; $\left.\cos 30^{\circ}=\frac{\sqrt{3}}{2}\right]$