Which explains why roman were upset by the emperors decision to create more coin?

Even without the options, the most obvious explanation why romans (those who had coin) were upset by the decision to create more coin is that when more of it was created, the value of the coin that the owners had was dilluted.

This happened because - if a certain person was perhaps the owner of 7% of all the coin that was available in the roman empire. After more coin was created, then he was the owner of 5% or less the available coin. That lowered his purchasing power and made him unsatisfied of course.