20. Which of the following situations creates a deadlock? X. Process A is waiting for data from process B. Process B has read data from process A and has yet to complete the computation. Y. Process A is waiting for data from process B. Process B is waiting for data from process C. Process C is waiting for A to provide data. Z. Process A wants to read data from file X once process B has finished writing to it. Process B is waiting for A to finish writing to file Y that A has locked. A. X only B. Y only C. Z only D. None of X, Y, and Z E. All, or two of X, Y, and Z