If I separated from the military on 02 December, 2019 what option would i click? Retired? Or was in the military all year?

When you enter your Info for yourself on the My Info page, on the main page you indicate that you were  a member during the year...then on a followup page, it asks your status on 31 Dec...and you will select the box for "I left the military in 2019" ....because you did