What is the arithmetic mean between a2 and b2 ?

• A. \(\frac {1}{2}\) (a – b)b) \(\frac {1}{2}\) (a +
• B. \(\frac {1}{2}\) (a + b)
• C. \(\frac {1}{2}\) (a2 – b2)
• D. \(\frac {1}{2}\) (a2 + b2)