Final answer:
Public opinion polls are not a major source of data on the extent of delinquency. They focus more on perceptions than actual incidents and can be subject to bias, as opposed to self-report studies like the National Crime Victimization Survey, longitudinal studies, and the Uniform Crime Reports.
Step-by-step explanation:
The question you have asked concerns identifying which option is not a major source of data on the extent of delinquency. The major sources available for researching the extent of delinquency include self-report studies, such as the National Crime Victimization Survey (NCVS), which collect data via questionnaires or interviews; longitudinal studies, which observe subjects over long periods of time; and the Uniform Crime Reports (UCR), published by the Federal Bureau of Investigation, which compiles official data from law enforcement agencies.
However, public opinion polls are not considered a major source of data on the extent of delinquency, as they often capture perceptions and attitudes rather than actual incidents of delinquency or crime. Such polls may be subject to bias and do not typically utilize the rigorous methodologies required for criminological research.