The correct option is B Seven years (1856−1863)
It was during the mid-nineteenth century that headway was made in the understanding of inheritance. Gregor Johann Mendel, conducted hybridisation experiments on garden peas for seven years (1856−1863) and proposed the laws of inheritance in living organisms. During Mendel’s investigations into inheritance pattern, it was for the first time that statistical analysis and mathematical logic were applied to problems in biology.