Find the next figure in the series.

Let's analyze the pattern of the inner triangle inside the square frames across the series:
1. In the first figure, the triangle points Upwards ($▲$).
2. In the second figure, the triangle points to the Right ($\text{black}forward$).
3. In the third figure, the triangle points Downwards ($▼$).

We observe that the triangle is rotating by $90^{\circ }$ clockwise in each step:

$$\text{Up}\to \text{Right}\to \text{Down}\to \text{Left}$$

Therefore, in the next (fourth) figure, the triangle must point to the Left ($\text{black}backward$).
Looking at the options, figure (A) contains a triangle pointing to the left inside the rectangular frame block.