Which of these give an expression for the mean of a discrete distribution?

• A. \( \int_{-\infty}^{\infty} xf(x)dx\)
• B. \( \sum_{i=1}^{\infty} x_i p(x_i)\)
• C. \( \sum_{i=1}^{\infty} (x-\mu)^2 p(x_i)\)
• D. \( \int_{-\infty}^{\infty} (x-\mu)^2 f(x)dx\)