The correct answer would be Choice B: 4 square units.
When the scale factor is 1/5, that means the lengths of the sides are 1/5 of the original size. So instead of having a base of 20 and height of 10, the new triangle has a base of 4 and a height of 2.
The resultant triangle frmo the dilatation would have 1/5 of the size on each size, in the original triangle the base is 10 units and the height is 20 units, so 1/5 of 10 would be 2, and 1/5 of 20 would be 4, the resultant triangle from the dilatation at 1/5 would have an area of 4 squared units.
The area of the triangle is calculated with the next formula:
so we know the radius of the semicircle is 2 and the rectangle below it is really a 4x4 square, so let's just get their separate areas and add them up.