-- Answer: b) a burial --
Paul speaks of baptism as being a burial in Colossians 2:12, just as he also does in Romans 6:3,4. Therefore, we don't even need to know the meaning of the original Greek word to understand that baptism is to be an "immersion" (a complete burial in water) -- and not a mere sprinkling or a pouring.
However, the Greek word "baptizo," which has been transliterated to "baptize," does mean "to dip, to plunge, to immerse."
If sprinkling were intended -- instead of immersion -- then the Greek word "rhantizo" could have been used. Or if "pour" were intended, the Greek word "ekcheo" could have been used. But neither of these terms is used; rather the Greek word "baptizo," and which best depicts a "burial" -- certainly more so than sprinkling or pouring would -- is what we find used in the New Testment for "baptize."