Proton Pumps Are Used in Various Ways by Members of Every

Proton pumps are used in various ways by members of every domain of organisms: Bacteria,Archaea,and Eukarya.What does this most probably mean?

A) Proton pumps must have evolved before any living organisms were present on Earth.
B) Proton pumps are an essential feature of all cell membranes.
C) Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.
D) Cells of each domain evolved proton pumps independently when oceans became more acidic.