If A and B are acute angles such that sin A = cos B then (A + B) = ?

Given: sinA = cosB

$\sin A=\cos B$

$\Rightarrow \cos \left(90^{\circ}-A\right)=\cos B \quad\left(\because \sin \theta=\cos \left(90^{\circ}-\theta\right)\right)$

$\Rightarrow 90^{\circ}-A=B$

$\Rightarrow 90^{\circ}=B+A$

$\Rightarrow A+B=90^{\circ}$

Hence, the correct option is $(\mathrm{d})$.