If a denotes some event, what does upper a overbar denote? if p(a)equals0.009, what is the value of p(upper a overbar)? if p(a)equals0.009, is upper a overbar unusual? what does upper a overbar denote? a. event upper a overbar is always unusual. b. event upper a overbar denotes the complement of event a, meaning that upper a overbar consists of all outcomes in which event a does not occur. c. events a and upper a overbar share all outcomes. d. event upper a overbar denotes the complement of event a, meaning that upper a overbar and a share some but not all outcomes.