The correct answer is option 4, Microcredit concept. Prof. Muhammad Yunus is renowned for his work in the area of microcredit. Microcredit is the practice of granting small loans to individuals who are typically unable to access traditional banking services. Prof. Yunus is considered the pioneer of microcredit, as he founded the Grameen Bank in Bangladesh in 1983, which provided small loans to impoverished individuals to start their own businesses and improve their economic conditions.

While Prof. Yunus has made significant contributions in other areas as well, such as poverty alleviation and social entrepreneurship, his most notable work and recognition comes from his role in developing and promoting the concept of microcredit. Through his efforts, millions of people around the world have been able to escape poverty and achieve economic empowerment.

Therefore, it is clear that Prof. Muhammad Yunus is renowned in the area of microcredit concept.