-- Answer: a) baptism --

Though many people believe that it is merely some type of "spiritual baptism" -- apart from the water -- which saves, Paul shows that the baptism involved is one in which a person can be buried in and raised up from -- water baptism. And that one is raised up from this baptism in order to be with Christ.

As Paul also shows in Romans 6:3,4, one is raised up from water baptism to "walk in newness of life."