Concept:Specialization is the practice of focusing on one specific job or task in order to become highly skilled and knowledgeable in that particular field.
Explanation:When a person remains on a single job, they direct all their effort toward mastering that specific role.
This consistent focus helps them to develop deeper expertise and become more efficient over time.
In commerce, the term for this act of concentrating on one job is specialization.
It must not be mixed up with separation of power, which involves sharing authority among different levels or arms of an organisation.
It is also different from immobility, which refers to the inability of a worker to move or change jobs.
It is not independence, because independence describes freedom from outside control or reliance on others.
The key feature in the question is that staying on one job is done for the purpose of gaining expertise.
Therefore, the correct term that matches this description is specialization.
Answer:D. specialization