Which of the following is an example of a requirement for a valid marriage in Illinois?

A valid marriage in Illinois requires that at least one partner must be a resident of the state. This ensures that the couple has a legal connection to the jurisdiction where they are marrying, which is essential for the marriage to be recognized under Illinois law. Residency requirements help maintain the state's interest in regulating marriages within its borders and ensure that the marriage complies with local laws and procedures.

The other options do not reflect requirements under Illinois law. For instance, consent from a family member is not a legal requirement for marriage; couples can marry without needing permission from family. Similarly, completing a premarital counseling program is not mandated by Illinois law. While some couples may choose to engage in such counseling, it is not a prerequisite for a valid marriage. Additionally, the venue of the marriage—whether religious or otherwise—is not a formal requirement for the legality of the marriage, as couples can marry in various settings, including civil ceremonies.

Thus, the requirement of residency is crucial for establishing a legal marriage in Illinois, making it the correct answer.