Crossing over – often, the sister homologous chromosomes of a cell exchange genetic material through recombination of genes.
Independent assortment/random fertilization – there are numerous variety of ways that the chromosomes of the gametes can combine, after meiosis, through fertilization to form a zygote
Mutation – on rare occasion, there is a slight and random change in the genes of a gametic cell caused by environmental factors.
The correct answer is; the open mouth of a baby robin is seen as a sign stimulus for the female robin (parent), and that the open mouth is the impending cause for her behavior.
