a. The potentially larger adverse selection problem arises with the optional policy covering fertility services for employees of Moderna. This is because employees opting for this policy likely have a higher demand for fertility services, leading to adverse selection where the insurance pool is predominantly composed of individuals with a higher likelihood of using these services. b. The potentially larger adverse selection problem occurs with the optional rider providing mental health coverage for an additional premium. Individuals opting for this rider likely have a higher demand for mental health services, resulting in adverse selection where the insurance pool is skewed towards those who anticipate higher mental health needs, potentially leading to increased costs for the insurer