Demography is the study of the vital statistics of populations and how they change over time?a. death and emigration rates of a population at any moment in time. b. the survival patterns of a population. c. life expectancy of individuals within a population. d. reproductive rates of a population during a given year.

Option A, death and emigration rates of a population at any moment in time

Explanation:

Demographic change primarily includes all the study of all those factors and variables that causes change in the size of the population and causes growth. The general formula of population change is (birth number– death number) + (immigration – emigration).  

Thus, its four vital study factors are birth rate, death rate, immigration and emigration and in some cases casual happenings and incidence leading to change in population change.  

Based on these four factors age structure graph are created and life expectancy, survival pattern and re-productivity/fertility pattern is studied.  

 Hence, option A is correct

thinking it would be physical characteristics

the missing space is phylum