If a, b, c are in hp, then b is related with a and c as _________

• A. 2(1⁄b) = (1⁄a + 1⁄c)
• B. 2(1⁄c) = (1⁄b + 1⁄c)
• C. 2(1⁄a) = (1⁄a + 1⁄b)
• D. None of the mentioned