Why would a roll crimp be a bad choice for a rimless straight-walled pistol case? 
a. A roll crimp on a rimless pistol case may create a crimp that is too tight, leading to a pressure spike. 
b. There is no issue with using a roll crimp on a rimless pistol case. 
c. A roll crimp on a rimless pistol case will not hold the bullet securely. 
d. A roll crimp on a rimless pistol case can create a headspace issue.