It is high time we----- on the matter.

The correct answer for the question "t is high time we----- on the matter." is "acted". The phrase "it is high time" is used to express that something should have happened already or that there is an urgent need for it to happen. In this case, the phrase suggests that some action should have been taken on the matter already. When using the phrase "it is high time," we typically follow it with the past tense verb. So, the correct answer is "acted", which is the past tense of the verb "act". This means that it is already overdue or necessary for us to have taken action on the matter.