Which expression expresses E[Y] for a distribution in the exponential family?

• A. E[Y] = c'(θ) / b'(θ)
• B. E[Y] = b'(θ) / c'(θ)
• C. E[Y] = θ
• D. E[Y] = - c'(θ) / b'(θ)

Answer: (D)