Which of the following is the most important arbitrage cost/risk for arbitrage trades involving multiple share-classes of the same firm, or dual-listed companies traded on the same exchange?

	A.	Direct trading costs (both current costs; and the uncertainty about future costs).
	B.	Short-selling costs (both current costs; and the uncertainty about future costs).
	C.	Horizon risk and idiosyncratic risk
	D.	Systematic risk
	E.	Exchange-rate (FX) risk