Population growth rate can be calculated as

Population growth rate measures how fast a country's population changes over time. It accounts for both natural change (births and deaths) and net migration (people moving in and out of the country).

The complete formula is:

\[\text{Population growth rate} = (\text{Birth rate} - \text{Death rate}) + (\text{Immigrants} - \text{Emigrants})\]

This can be rewritten as:

\[\text{Population growth rate} = \text{Birth rate} - \text{Death rate} + \text{Immigrants} - \text{Emigrants}\]

The birth rate minus death rate gives the natural increase in population. Adding immigrants (people entering the country) and subtracting emigrants (people leaving the country) gives the net migration effect. Together, these two components determine the overall population growth rate.

The formula "birth rate minus death rate" alone only captures the natural increase rate and ignores migration, so it is incomplete. The other options either misuse terminology (such as subtracting immigration from migration rate, which is redundant) or reverse the signs on immigrants and emigrants.