Color and luster are two ways to identify an unknown metal. Other ways include weight and composition.
The factor that helped the United States in making the inland transportation and commerce to be possible is in letter C. The intricate river system. I hope you are satisfied with my answer and feel free to ask for more if you have clarifications and questions.
B; As far as the relation between humans and the environment, it is obvious how much they relied on it. Not only as a food source, but for economic growth and sustainability as well. The other answers make valid points but in the context of this question, the only one that even mentions the relation is B.
Explanation:
Geography is the study of places and the relationships between people and their environments. Geographers explore both the physical properties of Earth's surface and the human societies spread across it.
History is the study of the past. Events occurring before the invention of writing systems are considered prehistory. "History" is an umbrella term that relates to past events as well as the memory, discovery, collection, organization, presentation, and interpretation of information about these events.