【单选题】

In a traditionally drawn decision tree，a circle represents______．
A．a chance to which no estimated monetary value can be assigned so that a likely pay-off can not be shown

B．a decision to which no estimated monetary value can be assigned so that a likely pay-off can not be shown
C．a chance to which an estimated monetary value may be assigned to calculate the most likely pay-off
D．a decision to which an estimated monetary value may be assigned to calculate the most likely pay-off