A supportive argument is an argument that is presented in favor of a particular point of view. It is typically composed of facts, evidence, and logical reasoning to support the main point. The term 'PRO' is an abbreviation for 'PROFESSIONAL, ' which is often used to describe someone who is knowledgeable and experienced in a particular field. Therefore, a PRO supportive argument is an argument that is presented by someone who is knowledgeable and experienced in the subject matter.