Answer: Municipal water and sewer
Explanation: A free entry occurs when there is no legal barrier or restriction preventing firms or startups from entering an industry. A free entry exist when a startup can freely begin production and marketing of certain goods or services once the startup has the required operational cost.
Of the options listed in the question above, Municipal water and sewer are mostly controlled by public organizations under the regulation of the Environmental Protection AGENCY (EPA) and the Safe Water Drinking Act (SWDA) utilizing tax charges paid by its citizens.