Mortality figures are normally developed by studying and interpreting statistics

a. from small groups of people over 10 yr periods of time
b. developed from the deaths of milllions of persons over long periods of time
c. gathered by interviewing many persons in selected cities across the nations
d. obtained by surveys of insured persons
b. developed from the deaths of milllions of persons over long periods of time

The correct answer is option B.

Explanation:

Mortality figures is rate or number that is express the death of millions of people over a very long periods of time that depend on various factors. These figures are derived from the the statics of that period of time and interpreting these data to collect essential data to generate mortality figure,  These figures base on large data therefore the studying these data and interpreting them are essential.

Thus, the correct answer is option B.