Who among the following is not a commercial occ?upaation

An engineer is not a commercial occupation. An engineer is a professional who applies scientific and mathematical principles to design and develop products, systems, and structures. While engineers may work in industries related to commerce, their profession is primarily focused on the design and development of products, rather than on buying, selling, or trading goods or services. In contrast, the other options listed in the question (stock broker, banker, common carrier, and advertising agent) are all occupations that are directly involved in commerce, such as buying and selling securities, providing financial services, transporting goods, or promoting products or services.