According to a controversial study published in the british medical journal the lancet, before the united states invaded iraq, about 5.5 people out of every thousand would die each year, but after the invasion, that number rose to over 13. this study was attempting to measure:

This study was attempting to measure "Mortality Rate".

A mortality rate is the quantity of passings amid a specific timeframe among a specific sort or gathering of individuals. Insurers base the premiums for disaster protection to some extent on the death rate for a proposed guaranteed's age gathering. 

Ais the correct answer