Determine whether the underlined conjunctions in the following sentence are coordinating or correlative by choosing the letters A (coordinating) or B (correlative).
Visitors to the Bureau of Engraving and printing in Washington can buy 150 dollars’ worth of United States currency for 75 cents, but there is a catch.
 A. A, B
 B. B, A
 C. A, A
 D. B, B