The color-based contrasting traits out of the seven contrasting pairs in pea plant that was selected for his experiments by Mendel were
Mendel selected seven pairs of contrasting characters like seed shape (round or wrinkled), seed color (green or yellow), pod shape (constricted or inflated), pod color (green or yellow), flower color (violet or white), plant height (tall or dwarf), and flower position (axial or terminal).
Out of these only three traits are color-based: Seed color, pod color, and flower color.