What is the benefit of implementing an HP solution in multisite phases as opposed one phase?

A.
The fact that multiple phases introduces more risks than one phase if offset by the shorter
network outage required for each phase.

B.
Components of the solution can be tested thoroughly between phases.

C.
The customer can achieve zero downtime, which is impossible when all changes are made
during single window.

D.
From start to finish, the complete solution is implemented more quickly.