A, C, and D all happen at different stages of a total lunar eclipse.
I'll describe the stages of the eclipse, but before I do, I just need to clarify: The Earth doesn't have an umbra or a penumbra, but its shadow does.
-- the eclipse begins when the first edge of the moon moves into the penumbra of Earth's shadow; ( C ) this part of the moon grows steadily.
-- After a while, the first edge of the moon begins to move into the umbra of Earth's shadow ( A ), and gets very dark.
-- The total phase of the eclipse begins when the ENTIRE moon is in the umbra of Earth's shadow.
Then everything happens in reverse.
-- Eventually, the leading edge of the moon moves out of the shadow's umbra, into the penumbra. This part steadily grows.
-- After a while, none of the moon is in the umbra, and the whole thing is in the penumbra. The moon is fully illuminated, but not quite as bright as it should be.
-- Soon, the leading edge of the moon leaves the penumbra of Earth's shadow, and gets brighter. This portion of the moon steadily grows, until ...
-- the moon completely leaves the penumbra, all of it is as bright as it's supposed to be. The eclipse is completely over. ( B )
==> The whole process lasts several hours.
==> Everybody on the night side of the Earth sees the same thing at the same time. It doesn't matter WHERE you are on the night side ... if you can see the moon in the sky, you see the present phase of the eclipse.
==> The lunar eclipse can only happen at the Full Moon. In fact, the mid-point of the total phase is the exact moment of Full Moon.
