Answer:
A (one allele from each parent)
Explanation:
According to Mendel's experiments, an organism receives two forms of a gene called allele, one from each parent. He discovered in his law governing heredity that an organism will undergo meiosis and each of its gene variant (allele) will get separated into gametes (law of segregation). These gametes randomly combine when mated to yield two alleles in each offspring i.e. one from the male parent and one from the female parent.
He crossed pea plants in his experiment to observe the height trait. He crossed purebreeding pea plants that are homozygous dominant (Tall, TT) and recessive (short, tt). He realized that the F1 offsprings possess two alleles that is a combination of both alleles from the parent i.e. Tt.
He also realized that all the F1 offsprings are tall, which brought about his law of dominance, which says that an allele is capable of masking the expression of another in a heterozygous state. The allele that masks is called DOMINANT allele while the allele that is masked or covered up is RECESSIVE allele.
Hence, the F1 offsprings received a dominant allele (T) and recessive allele (t) from each parent to make up their genotype.
