Which of the following best describes the main idea of the passage? A. Homo economicus is a useful, if theoretical, actor to use in the formation of mathematical models. B. Homo economicus is a fundamentally flawed and thus theoretically useless construction, for a host of reasons. C. Homo economicus is often criticized by those who don't fully understand its function in economic theory. D. Homo economicus is a problematic construction, because it simplifies human motivations and is overly optimistic about human understanding. E. Homo economicus fell out of favor with most economists in the 20th century due to its many incorrect assumptions about humanity.