Every subscriber under a dental or optometric service plan must receive a copy of the contract. The contract must clearly state the care, appliances, materials, and supplies to be provided under the contract and the rate charged the subscriber. Every subscriber must have, at all times, free choice of the dentist or practitioner who is to treat the subscriber, and this right must be prominently printed in the contract. Every optometric service contract must provide that a subscriber has the freedom of choice to have the materials and supplies furnished by any practitioner or optician, the cost for which is to be covered in accordance with the terms of the contract.