The correct answer to this open question is the following.
Although there are no options attached we can say the following.
The fact that Profesor "T" discovered that a large percentage of the students who sign up for his course are only looking for the easiest way to get a high grade and are uninterested in learning the subject is an example of the Principle of least effort.
The Principle of least effort is a theory that proposes that humans are always looking for the easiest ways to do things or those things that require less effort to accomplish things.
It says that individuals do not like to effort and thrive. For people, the easiest way, the better.
That is why students, knowing the reputation of professor "T" of being an easy grader, sign up for his course only looking for the easiest way to get a high grade and are uninterested in learning the subject.