If V₁ is the jet velocity and V₀ is the vehicle velocity, then propulsive efficiency of a turbojet engine is

• A. V₁ / (V₀ + V₁)
• B. V₀ / (V₀ + V₁)
• C. 2V₀ / (V₀ + V₁)
• D. 2V₁ / (V₀ + V₁)