Fifteen-year-old Mary has become critical of her parents and siblings, yet envisions a world with no injustice or discrimination. This is typical of the __________ that manifests during the development of abstract reasoning

Even on the clearest night, some stars cannot be seen by the naked eye because they are below the viewer's __________ threshold

FIll in the blank with correct word.

Chuck goes to work five days a week, but gets paid after every two weeks. What schedule of reinforcement is this?

a. variable interval b. fixed interval c. variable-ratio d. fixed-ratio