A Light Wave with an Electric Field Amplitude of E₀ $\pi$

A light wave with an electric field amplitude of E₀ and a phase constant of zero is to be combined with one of the following waves. Which of these combinations produces the greatest intensity?

A) wave A has an amplitude of E₀ and a phase constant of zero
B) wave B has an amplitude of E₀ and a phase constant of $\pi$
C) wave C has an amplitde of 2E₀ and a phase constant of zero
D) wave D has an amplitude of 2E₀ and a phase constant of $\pi$
E) wave E has an amplitude of 3E₀ and a phase constant of $\pi$