Write an equation that demonstrates how pure water can act as both a Bronsted-Lowry acid and Bronsted-Lowry base at the same time.

a) H₂O → H⁺ + OH⁻
b) H⁺ + OH⁻ → H₂O
c) H₂O + H⁺ → H₃O⁺
d) H₂O + OH⁻ → O₂ + H₂