Which of the following does NOT explain the characteristics of an expansion path?

	A.	An equal proportionate increase in the price of both labour and capital does not shift the expansion path.
	B.	Along an expansion path, the input price ratio is constant.
	C.	The expansion path is a locus of efficient input combinations for each level of output.
	D.	An increase in the price of two inputs always causes a shift in the expansion path.