so you can say that MRP naturally varies
e.g. a lawyer has a high MRP due to the skill involved- they did training, education, sacrificed earlier wage-earning in order to study, they have stress at home etc etc.
Then state that this is different to a cleaner who doesnt have as many qualifications, no stress to carry etc.
Therefore, MRP has led to a wage differential as the lawyer and cleaner are paid differently as the lawyer generates more revenue for the firm so the money value of their work is higher. A cleaner makes no additional revenue and can be easily replaced.