Answer:
Option: a. showed that U.S.-born children had different head shapes than their immigrant parents.
Step-by-step explanation:
Franz Boas a German American anthropologist, known as Father of Modern Anthropology. He became the first to perform the scientific method to analyse human societies and cultures. He became the prominent figure in the 20th century in America. He showed that the child born in America has a different cranial size than his immigrant parents. Boas explained this theory by arguing that the environment influences these features. The changes have occurred throughout time.