Marine regression means that, submerged sea floor are exposed. It exposes the sea bottom while the transgression may result into flooding. A sea level transgression or marine transgression means when the water level or sea level arises in land, it also means that the sea level will move towards higher land.
C) 3 Moles
This is because of the molecular structure shown in the image
boiling point - condensation point
is the answer i would choose because it makes more scene