Human capital is the stock of knowledge, skills, abilities, and experience that individuals possess, which can be utilized to contribute to economic productivity. It refers to the investment made in the education, training, and development of individuals, as well as their health and well-being.

Qualitative improvement in labour:
Human capital investment leads to qualitative improvement in labor by enhancing the knowledge, skills, and abilities of individuals. This improvement enables them to perform their tasks more efficiently and effectively, leading to higher productivity and economic growth. Here are some key points that explain why human capital investment brings qualitative improvement in labor:

1. Education and Training: Investing in education and training programs equips individuals with the necessary knowledge and skills required for their respective fields. This enables them to perform their tasks with greater expertise and precision.

2. Enhanced Problem-Solving Abilities: Human capital investment helps individuals develop critical thinking and problem-solving abilities. This enables them to analyze complex situations, identify solutions, and make informed decisions, thereby enhancing their contribution to the labor market.

3. Adaptability and Flexibility: Continuous investment in human capital allows individuals to adapt to changing work environments and technological advancements. They can quickly learn new skills and technologies, making them more adaptable and flexible in their jobs.

4. Innovation and Creativity: Human capital investment fosters innovation and creativity by providing individuals with the necessary tools and knowledge to generate new ideas and approaches. This leads to the development of new products, services, and processes, which contribute to economic growth.

5. Health and Well-being: Investing in the health and well-being of individuals improves their overall productivity and performance. It reduces absenteeism, promotes physical and mental well-being, and enhances their ability to contribute effectively to the labor market.

Conclusion:
In conclusion, human capital investment brings qualitative improvement in labor by enhancing individuals' knowledge, skills, abilities, and well-being. This improvement leads to higher productivity, economic growth, and innovation. Therefore, the correct answer to the question is option B, as human capital investment primarily focuses on qualitative improvement in labor.