On the first day of fall, .

Drastic boundary changes can occur for all of the following reasons except for a. a shift in the way a river flows b. the collapse of a government system c. a conflict between two neighboring groups d. one country's decision to sell land to another country select the best answer from the choices provide

The graph below plots the temperature and luminosity of stars on the main sequence.

Which phrase describes the time it takes for a planet to make a complete rotation