A person commits criminal sexual assault if committing an act of _____ and uses force or the threat of force.

The definition of criminal sexual assault in Illinois law specifically involves the act of sexual penetration, accompanied by the use of force or the threat of force. This means that for an act to be classified as criminal sexual assault, there must be an element of physical violation that goes beyond mere unwanted sexual contact or conversation. The emphasis on "sexual penetration" establishes the severity of the offense, as it indicates a more invasive and non-consensual act.

Sexual penetration is legally defined and encompasses a range of violations, making it a more serious crime than the other options presented. Terms like sexual conversation, sexual abuse, and sexual manipulation do not correspond to the specific legal threshold for criminal sexual assault as defined in Illinois law. Therefore, the reference to sexual penetration directly aligns with the legal framework surrounding this crime, supporting the correctness of this answer.