(A) Yes,the two triangles will be similar.
Let the two right-angled triangles be $\triangle ABC$ and $\triangle PQR$,where $\angle B = \angle Q = 90^{\circ}$.
Given that one acute angle of the first triangle is equal to an acute angle of the second triangle,let $\angle A = \angle P$.
In $\triangle ABC$ and $\triangle PQR$:
$1$. $\angle B = \angle Q = 90^{\circ}$ (Given)
$2$. $\angle A = \angle P$ (Given)
By the $AA$ (Angle-Angle) similarity criterion,since two angles of one triangle are equal to two angles of the other triangle,the triangles are similar $(\triangle ABC \sim \triangle PQR)$.
This is also a specific case of the $AAA$ similarity criterion,as the third angles must also be equal due to the angle sum property of a triangle.