Joiner transformations

It is desired to join together a database table, a flat file and an XML file. All three sources have a single common field called CUSTOMER_ID. What is the minimum number of Joiner transformations that are needed to join these sources?

Choose Answer

(A)
One
(B)
Two
(C)
Three
(D)
One if the flat file and the XML file are located in the same directory, two if they are located in different directories.