The Blackbird - SR-71 Question

This cards states the following:
We were having a discussion about this, does the opponent has to pay 1 for each character to block? Or does it have to pay 1 to block every character?
Your opponent must pay 1 to block each of your X-Men character dice (until end of turn)
We were having a discussion about this, does the opponent has to pay 1 for each character to block? Or does it have to pay 1 to block every character?