(a) Mendel choose pea plants for studying inheritance because pea plants had a number of clear cut differences which were easy to tell apart. Another reason for choosing pea plants are they were self pollinating and many generations can be produced in a short time span.

(b) According to Mendel’s second law of inheritance:

In the inheritance of more than one pair of traits in a cross simultaneously, the factors responsible for each pair of traits are distributed independently to the gametes.