In the Context of a Public Goods Game, If a Participant

In the context of a public goods game, if a participant is a conditional co-operator then which of the following statements is true?

A) Regardless of this participant's beliefs about other participants actions, she should always free-ride.
B) Her contributions to the public account will be positively correlated with her beliefs about the contributions of her group members.
C) Regardless of this participant's beliefs about other participants actions, she should always contribute her entire token endowment to the public account since this will help attain the social optimum.
D) She should match the contribution of her group members up to a point but she should reduce her contributions beyond that.