Choose the correct equation for finding the output of a discrete time convolution?

• A. y[n] = ∑x[k]h[n-k], k from 0 to ∞
• B. y[n] = ∑x[k]h[n-k], k from -∞ to +∞
• C. y[n] = ∑x[k]h[k], k from 0 to ∞
• D. y[n] = ∑x[k]h[n], k from -∞ to +∞