An MCO shall provide to its enrollees medically necessary primary care services that are provided: By the enrollee's PCP; At the direction of the enrollee's PCP; or With respect to a primary care service that is self-referred pursuant to Regulation .28 of this chapter: By an appropriate practitioner, acting within the scope of the practitioner's license, certification, or other legal authorization, and in accordance with the practitioner's training and experience; or By a clinic that furnishes health care services by or under the direction of a physician.