A.  The best performance expectation one can have is measured in seconds. This is because Hadoop can only be used for batch processing
B.  The best performance expectation one can have is measured in milliseconds. This is because Hadoop executes in parallel across so many machines
C.  The best performance expectation one can have is measured in minutes. This is because Hadoop can only be used for batch processing
D.  It depends on on the design of the map-reduce program, how many machines in the cluster, and the amount of data being retrieved

Answer: A