Answer: Solution: When FG∥BC and HP∥AB, the relationship between the areas of the two shaded parts in the figure is uniquely determined.
Reason: ∵ Quadrilateral ABCD is a parallelogram,
∴∠A=∠C, AB∥CD, AD∥BC,
∵AB∥PH, EF∥AD,
∴AD∥FG∥BC, AB∥HG∥CD,
∴∠ADB=∠DBC, the quadrilateral EFBP and the quadrilateral DHEG are parallelograms,
∵In △DAB and △BCD
∠A=∠C∠ADB=∠DBBCD=BD,
∴△DAB≌△BCD (AAS),< /p>
∴S△DAB=S△BCD,
Similarly, S△DHE=S△DEG, S△EFB=S△BPE,
∵S quadrilateral AFEH=S△ABD-S△BFE-S△DHE, S quadrilateral EPCG=S△BCD-S△BEP-S△DEG,
∴S quadrilateral AFEH=S quadrilateral EPCG
< p>∴When FG∥BC and HP∥AB, the size relationship between the areas of the two shaded parts in the figure is uniquely determined.So choose: C.