Part A.
The area of a triangle is given by the product of its base and the height relative to that base.
Since these triangles have the same base b and same height h, they have the same area.
Part B.
The area of a rectangle or parallelogram is given by the product of base and height. Since these figures have the same base and height, they have the same area.
Part C.
These figures have different shapes, so we can't affirm that they have the same area.
Part D.
The height shown in the image is not the height relative to side b, therefore we can't affirm that the triangles have the same area.