Which of the following statements about the MapReduce framework are correct?
a. An input file is split into a number of pieces, which are then processed by a number of reduce workers in parallel.
b. Map workers are responsible for sending their outputs to reduce workers.
c. Completed map tasks cannot be re-executed in any case, in order to avoid data inconsistency.
d. The key/value pairs generated by map workers are sorted, and then sent to the master for further processing.
e. MapReduce is a programming model that can parallelize and distribute some simple computation tasks