Final answer:
In a situation featuring both relationship and individual complaints, substance abuse should be addressed first, as it poses an immediate risk and can exacerbate other marital issues.
Step-by-step explanation:
In the context of an initial marital therapy session where both partners report significant complaints about one another's behavior, it's important to prioritize the issues that pose the most immediate risk to both individuals. From the four options given, substance abuse should generally be addressed first, as it can have a direct and profound impact on both the safety and well-being of the individuals. It's important to address alcohol use because it can exacerbate other issues such as anger, control, and sexual conflict, potentially leading to more severe consequences such as domestic abuse and financial instability. Substance abuse can also create a barrier to effective communication and problem-solving within the marriage, which is critical for marital therapy.