Answer:
The law of dominance
Step-by-step explanation:
This cross (aabb x aabb) is an example of a double homozygous recessive cross. When organisms with recessive traits are crossed among themselves, the offspring will all show the recessive traits. Conversely, when one of the parents (or both) has a dominant allele for one of the genes, the offspring will show the dominant trait in a given proportion which normally is larger than the offspring with the recessive traits. These crosses led Mendel to propose the law of dominance.