In terms of legal marriage, which of the following is required in Illinois?

In Illinois, one of the fundamental requirements for a legal marriage is that the parties must not be related by blood. This reflects the legal principle of consanguinity, which prohibits marriages between close relatives to prevent genetic issues and uphold social norms. Marriages between certain close relatives, such as siblings or parents and children, are not recognized in Illinois law, ensuring that these relationships do not occur legally.

While some of the other choices touch on important aspects of marriage, they do not hold as universal requirements in Illinois. For example, being a U.S. citizen is not necessary for marriage, as non-citizens can also legally marry in the state. Additionally, while having a driver's license may be useful as a form of identification when obtaining a marriage license, it isn't a legal requirement for the validity of the marriage. Lastly, Illinois does not impose a waiting period of 30 days before a marriage can take place; couples can typically marry right after obtaining their marriage license, as long as they comply with the necessary legal provisions. Thus, the prohibition against marrying close relatives is the most definitive and recognized requirement in this context.