What is infant mortality rate?

The correct option is D Number of deaths of infants under one year old in a given year per 1,000 births in the same year
Infant mortality rate is the number of deaths per 1,000 live births of children under one year of age. The rate for a given region is the number of children dying under one year of age, divided by the number of live births during the year, multiplied by 1,000