What offense is committed when a couple is found engaging in sexual activity in public?

Public indecency is the correct answer because it specifically refers to the act of engaging in sexual activity or exposing one's genitals in a public place where others are present. Laws define public indecency to protect societal norms regarding sexual behavior in public settings. Engaging in sexual activity in public is a clear violation of these norms and can lead to legal repercussions.

Public disturbance generally pertains to disruptive or disorderly conduct in a public setting but does not specifically address sexual acts. Indecent exposure involves revealing one's private parts, but the key focus here is the act of sexual activity itself. Distracting conduct could describe various behaviors, but it lacks the specificity related to sexual acts or nudity.

Thus, public indecency aptly captures the criminal nature of engaging in sexual activity in a public context.