Answer: The correct answer is-
D. Factors for some traits are inherited from parents.
Gregor Mendel studied certain traits in pea plant and deduce the pattern of their inheritance using various experiments. According to Mendelian inheritance pattern, a characteristic or trait in an organism is depicted by single gene loci.
In other words, a single gene that exist in two alternative forms ( also known as alleles, which are dominant and recessive allele) depicts a particular trait (such as pea shape, pea color, height of pea plant).
He discovered that for some traits in organisms, factors are inherited from parents to their offspring ( that is from one generation to another) and these factors were later called genes ( also known as unit of heredity).
Thus, option D) is the right answer.