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 forms of infrastructure investments is the most liquid?
Option A:An unlisted infrastructure mutual fund
Option B:A direct investment in a greenfield project
Option C:An exchange-traded master limited partnership (MLP)

Answer: C