Answer: The optimal price is higher than market price by less than $0.50.
Step-by-step explanation:
Since, it was given that Coase theorem doesn't hold in this situation, hence, the social marginal cost is greater than the private marginal cost by $0.50. The social marginal cost curve lies towards the left of demand curve.
Since the demand and supply curve are not perfectly elastic or inelastic, so the optimal equilibrium occurs at a point (price) which is greater than the prevailing market price, but the difference in the price is less than $0.50.
Therefore, the optimal price is higher than market price by less than $0.50.