One psychological study investigated whether intelligence declines with age. Experimenters took subjects from different age groups, running from late childhood
through old age, administered IQ tests to each age group and then looked how the
results changed from one age group to another. What method of observation did the
researchers use?

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