Given a text T, and several options, according to the question posed in the text T to choose the most appropriate option from the options as the answer, please directly output the most appropriate option, do not need to output the explanation.

Which of the following market regulations will most likely impede market efficiency?
Option A:Restricting traders’ ability to short sell.
Option B:Allowing unrestricted foreign investor trading.
Option C:Penalizing investors who trade with nonpublic information.

Answer: A