Final answer:
The Social Disorganization Theory proposes that youth with a history of violence and crime join gangs and continue their delinquency after becoming gang members.
Step-by-step explanation:
The explanation of gang activity that proposes that youth with a history of violence and crime join gangs and continue their delinquency after becoming gang members is the Social Disorganization Theory. This theory suggests that crime is more likely to occur in communities with weak social ties and the absence of social control. Individuals who grow up in impoverished neighborhoods with high rates of drug use, violence, and delinquency are more likely to become involved in crime compared to those from wealthier neighborhoods with a good school system and positive community involvement.