Which of the following rates measures how many children are being born in a country (in relation to the size of its population)? a. birth rate b. migration rate c. urbanization rate d. death rate

It is the birth rate because the other answers do not fit. Migration rate would be the rate at which people move to the country, meaning they weren't born there. Urbanization rate has to do with the movement of people to urban areas, which has nothing to do with birth. Death rate has to do with the death of people in a country which is the opposite of being born. Therefore, A is the only logical answer. 

It is the doctrine that the us had the right and duty to expand throughout north america. it just means they believed they had the right to expand westward and they did! they stated with the 13 colonies and then they kept moving gaining different territories throughout the years