Answer:
C. Lack of personal meaningfulness in the work
Step-by-step explanation:
A strainful job is not necessarily a meaningless job. Some jobs with heavy workload and excessive workloads can be meaningful, for example, many doctors in urgent care find their work immensely meaningful despite having to work for very long periods of time, in schedules that vary a lot (one day the may work in the morning, the next day the may have to pull an all-nighter).
On the opposite, an easy job can be meaningless. People who sit in front of a computer all day with hardly anything to do tend to get bored and anxious.