If you know an index fossil existed between 20 and 15 million years ago, what can you assume about the age of the rock in which the index fossil is found?

The diagram shows the results when two parents are crossed. the letters represent alleles for a trait that is controlled by three different genes. which best describes this inheritance pattern? multiple allele because a trait is controlled by three different genes polygenic because the offspring have alleles from both parents multiple allele because the offspring have alleles from both parents polygenic because a trait is controlled by three different genes