Answer:
B. they wanted to know what inspired an act of violence
Explanation:
Although there isn't enough information, I'm assuming this refers to the study made by Stephen and Rachel Kaplan. Their study was aimed towards explaining the impact environment has on one's (or population's) happiness.
The idea started long ago, after John F. Kennedy's assassination and the situation that followed.
They wanted to know what was the cause of such a violent crime and tried to link that to the unhealthy environment, or in other words, could that violence be the consequence of an unhealthy environment.
Their study was supposed to determine what are the characteristics of a desired environment, what impacts it has on people and what conditions it needs to meet in order to contribute to the well-being of the population.
