As the Size of a Crowd Increases,people Are Less Likely

Multiple Choice

As the size of a crowd increases,people are less likely to help someone who is in distress.What is the relationship between the number of people in a crowd and the likelihood of helping

A)  They are negatively correlated. 
B)  They are indirectly correlated. 
C)  They are uncorrelated. 
D)  They are positively correlated.