How many true-breeding pea plant varieties did Mendel select as pairs, which were similar except in one character with contrasting traits?

The correct option is A

14

The correct option is A.

Explanation for the correct option:

1. When a plant undergoes continuous self-pollination and shows a stable inheritance of a particular trait and it gets expressed for several generations, it is known as a true breeding line.
2. Gregor Mendel chose 14 true-breeding varieties of pea plants in pairs that were alike exception being one trait with differing characteristics.
3. List of all pairs of contrasting features:
   1. Colour of Pea (green or yellow)
   2. Colour of Pod (green or yellow)
   3. Size of Plant (tall or dwarf)
   4. Position of flowers (axial or terminal)
   5. Shape of Pod (constricted or inflated)
   6. Colour of Flower (purple or white)
   7. Shape of Pea (round or wrinkled)

Final answer: Mendel selected 14 true-breeding pea plant varieties as pairs which were similar except for one character with contrasting traits