What best describes why the critical angle of an air-glass boundary is 39.3°? A. It is the angle of refraction in glass for which the angle of incidence in air is 90°. B. It is the angle of incidence in air for which the angle of refraction in glass is 90°. C. It is the angle of refraction in air for which the angle of incidence in glass is 90°. D. It is the angle of incidence in glass for which the angle of refraction in air is 90°.

In 1859, charles darwin published the first edition of on the origin of species, which explained his observations of various groups of animals that showed great similarities but minor differences. darwin concluded that if a population of one species separates into two different populations that live in separate locations, then over the course of many generations the different populations can develop into different species. this idea predicted many future biological findings and became the basis of modern biology. darwin’s explanation for why different species exist is best described as a(n) law. theory. inquiry. hypothesis.