Aside from low birthrates and high death rates what can cause a country population to decline

Which of the following is a measure of the amount of light a star directly emits? a. luminosity b. wavelength c. brightness d. intensity

On this map of the united states the letter h indicates high pressure and the letter l indicates low pressure . select the black arrow that accurately shows the direction of the wind.

Identify the youngest layer in the figure ( have to click one letter)