Mr X Values a Good at $100 and Buys It

Mr. X values a good at $100 and buys it from Mr. Y at $80 (who produces it at a cost of $70) . Mr. Z then offers Mr. X the same good at $60. Mr. X buys the good from Mr. Z, and stops buying it from Mr. Y. Which of the following makes this event to be Pareto optimal

A) Mr. X gives Mr. Y $11.
B) Mr. X gives Mr. Y $30
C) Mr. X pays Mr. Z $80.
D) Mr. X and Mr. Z join to give Mr. Y $70.