The owner of a small convenience store wants to replace his old inventory tracking system with a new one. He hires Juan, a software developer, to create a new inventory tracking system. The convenience store owner wants Juan to train his employees before Juan integrates the new system and wants the process to be as cost effective as possible. Juan decides to shut down the old system completely before installing the new one. Which integration method should Juan use?

A.
direct changeover
B.
phased method
C.
pilot method
D.
parallel running