Perforation during Lap cholecytectomy

Q.     Regarding Lap Cholecystectomy false  is  (AIIMS) 

a.       GB perforation occurs in 40%

b.      Perforation occurs at time of dissection from GB bed

c.       10 – 30 % incidence of missed stones in peritoneal cavity

d.      Missed stones seldom cause any problem in the future