Change the sentence "He likes swimming" to the infinitive form.

The transformation to the infinitive form requires changing the verb in the original sentence into its infinitive structure while maintaining the original meaning. In the case of "He likes swimming," the correct infinitive form is achieved by saying "He likes to swim."

This construction effectively captures the sense of enjoyment conveyed by "likes" while introducing the infinitive "to swim." It maintains the intended message that swimming is something he enjoys.

Other choices do not fit the requirements as accurately. For instance, "enjoys to swim" is incorrect because "enjoy" typically requires the gerund form rather than the infinitive. "Prefers to swim" changes the meaning slightly by suggesting a preference rather than simple enjoyment. "He is fond of swimming" does express a liking for swimming but does not convert to the infinitive form and alters the phrasing significantly. Thus, "He likes to swim" is the clearest and most accurate transformation.