Three activities are candidates for crashing on a project network for a large computer installation $($ all are, of course, critical $).$ ?Activity details are in the following table:

a $)$ ?Activity that should be crashed first to reduce the project duration by $1$ ?day is

b $)$ ?Activity that should be crashed next to reduce the project duration by one additional day is $B$

c $)$ ?Total cost of crashing the project by $2$ ?days $=$ $

$($ Enter your response as an integer. $)$