问题如下：
Which of the following market regulations will most likely impede market efficiency?
选项：
A.Restricting traders’ ability to short sell.
B.Allowing unrestricted foreign investor trading.
C.Penalizing investors who trade with nonpublic information.
解释：
A is correct.
Restricting short selling will reduce arbitrage trading, which impedes market efficiency. Permitting foreign investor trading increases market participation, which makes markets more efficient. Penalizing insider trading encourages greater market participation, which increases market efficiency.
请问为什么C不对？
