Introduction:
Rural-urban migration refers to the movement of people from rural areas to urban areas in search of better opportunities and improved living conditions. It is a complex phenomenon influenced by various factors. In this context, option 'D' states that none of the above options are the cause of rural-urban migration. Let's analyze each option to understand why it is not a cause of rural-urban migration.

Analysis:

a) High demand of labors in urban areas:
- The high demand for labor in urban areas is one of the main causes of rural-urban migration.
- Urban areas, with their industries, services, and infrastructure, require a large workforce to sustain economic growth.
- As a result, individuals from rural areas migrate to urban areas in search of employment and better wages.
- This option is incorrect as it is indeed a cause of rural-urban migration.

b) Low job opportunities in rural areas:
- Low job opportunities in rural areas can also contribute to rural-urban migration.
- Rural areas often lack diverse industries and have limited job prospects, especially for skilled workers.
- The absence of economic opportunities pushes individuals to migrate to urban areas where there are more job options.
- This option is also incorrect as it is a cause of rural-urban migration.

c) Unbalanced pattern of development between urban and rural areas:
- An unbalanced pattern of development between urban and rural areas is a significant cause of rural-urban migration.
- Urban areas tend to receive more investment, infrastructure development, and access to services compared to rural areas.
- This disparity in development creates a pull factor for individuals to migrate to urban areas in search of a better quality of life.
- This option is incorrect as it is a cause of rural-urban migration.

d) None of the above:
- This option is the correct answer according to the given statement.
- However, it is important to note that all the options mentioned above are indeed causes of rural-urban migration.
- Therefore, option 'D' is incorrect in the context of the question.

Conclusion:
In conclusion, rural-urban migration is influenced by various factors, including the high demand for labor in urban areas, low job opportunities in rural areas, and an unbalanced pattern of development between urban and rural areas. While option 'D' suggests that none of the above options are the cause of rural-urban migration, it is incorrect as all the options mentioned are valid causes of this phenomenon.