When is the best time to think about security when building an application?

AStart the application development phase, and when you reach the halfway point, you have enough of a basis to look at to decide where and how to set up the security elements.

BFrom the planning and design phase and through the whole development life cycle.

CBuild the application first and then add a layer of security.

DNo security needs to be developed inside of the code itself. It will be handled at the operating system level.