What did the Catholic Church officially declare about indulgences in the Councils of Trent?

A: They had become too corrupted and unpopular to use in the future.
B: They were a valuable tool but needed to be used correctly.
C: They had been an error that should not have been issued, but the reformers were still wrong in how they protested them.
D: The Church had never erred in their use and would never stop issuing them.