Crude birth rate is a simplest measure of fertility because it includes:

Correct option is B

Sol. The crude birth rate (CBR) is calculated by taking the number of live births in a given year divided by the mid-year population of that year, multiplied by 1000.
Explanation of each option:
· (a) Total population – This is incorrect. The total population includes people of all ages, but CBR uses the mid-year population, not the total population.
· (b) Mid-year population – Correct answer. CBR uses the mid-year population to calculate the birth rate per 1000 people.
· (c) Live births only – While CBR focuses on live births, it is not the only factor. It is used in combination with mid-year population for the calculation.
· (d) Pre-term births – This is incorrect. Pre-term births are not specifically included in the calculation of CBR, which focuses on all live births.