GKFix MCQ Question

What is the formula for calculating the average atomic mass of an element?

• A. (A1 + A2 + ... ) / (x1 + x2 + ... )
• B. (A1x1 + A2x2 + ... ) / (x1 + x2 + ... )
• C. (A1 + A2 + ... ) × (x1 + x2 + ... )
• D. (A1x1 + A2x2 + ... ) × (x1 + x2 + ... )