Labour as a factor of production is easily available, especially in countries like India. The land is a limited resource that cannot be created. Capital is an expensive factor and hence is not easy to procure. Entrepreneurship requires skill, ability and knowledge.
But, as far as labour is concerned, it can be skilled or unskilled, owing to the unemployment, is easy to procure. Thus, we can say that, out of all the other factors of production, it is most abundant.
Hence, the correct answer is B.