For perfect intercooling in a three stage compressor

• A. p₂/p₁ = p₃/p₂ = p₄/p₃
• B. p₃/p₁ = p₄/p₂
• C. p₁ p₂ = p₃ p₄
• D. p₁ p₃ = p₂ p₄