Which of the following can be used to undo the effect of parttion by round robin?

Interleave is the correct component to undo a 'partition by round robin' operation. Round robin distributes rows sequentially across multiple partitions, and Interleave reverses this by reading from partitions in a round robin fashion to restore original order. Gather would lose the ordering, Broadcast is for duplicating data, and 'Mege' is misspelled.