Mendel chose contrasting traits in Pea
Gregor Johann Mendel, an Austrian Monk, discovered the principles of heredity through the experiments on the pea plant. Mendel conducted hybridization experiments on garden peas for seven years and proposed the laws of inheritance in living organisms. Mendel selected 14 true breeding pea plant varieties, as pairs which were similar except for one character with contrasting traits.
So, the correct option is ‘Seven’