Achance creation of a new allele is called a

The correct option will be option D (Each parent passes on only one factor for each trait to its offspring).

Explanation:

Gregor mendel worked on the pea plants and discovered the "fundamental laws of inheritance".

The law of Segregation states that inherited trait occur in two genetic alleles copies which randomly separates during gamete formation with each gamete receives only one genetic allele which reunite during fertilization. Therefore, offspring inherit one genetic allele from each parent. For example:

         Parents :                              Yy         X        Gg

                                                      ↓                        ↓

        Offsprings :                 Y   ←    →   y         G  ←   → g

Thus, option D is the correct answer.