Which of the following is NOT an example of something that could be described as onerous?

The correct identification of "a light workload" as something that is not onerous is based on the meaning of the term "onerous." Onerous refers to something that is burdensome, oppressive, or difficult to bear. When describing a workload, "onerous" implies it involves significant effort, stress, or weightiness.

In contrast, a light workload suggests a manageable level of responsibility that typically does not induce stress or exhaustion. It lacks the qualities that would make a task or responsibility onerous. Therefore, it stands apart from the other options, which all imply a level of difficulty or pressure associated with them. A heavy burden of responsibility, a demanding task, and an exhausting obligation all indicate a higher degree of challenge and discomfort, aligning well with the definition of being onerous.