What is the correct upgrade procedure?

You want to upgrade a cluster with two members to R77. The Security Management Server and
both members are version NGX R65, with the latest Hotfix Accumulator. What is the correct
upgrade procedure?
1. Change the version in the General Properties of the Gateway-cluster object.
2. Upgrade the Security Management Server, and reboot.
3. Run cpstop on one member, while leaving the other member running. Upgrade one member at
a time and reboot after upgrade.
4. Install the Security Policy.

A.
3, 2, 1, 4

B.
2, 4, 3, 1

C.
2, 3, 1, 4

D.
1, 3, 2, 4