A retail company is expanding its digital footprint by launching an online platform aimed at selling products directly to consumers. The platform must offer a seamless, secure, and personalized login experience, supporting various authentication methods such as social media logins and biometrics. Additionally, it should enable personalized user journeys based on customer preferences, ensuring a tailored shopping experience. The solution must be cost-effective, scalable to handle future growth, and fully compliant with global data protection regulations like GDPR. Considering these requirements, which Azure service is the most suitable for implementing a secure, scalable, and compliant identity management solution that supports a wide range of authentication methods and personalized user experiences? (Choose one option from A, B, C, D)