If a₁, a₂, a₃ are in airthemetic as well as geometric progression then which of the following is/are correct?

• A. 2a₂ = a₁ + a₃
• B. a₂ = (a₁a₃)½
• C. a₂ – a₁ = a₃ -a₂
• D. All of the mentioned are correct