Final answer:
Amazon Aurora is an RDS DB product that supports HA where all instances can be used for writes.
Step-by-step explanation:
The Amazon Relational Database Service (RDS) product that supports High Availability (HA) where all instances can be used for writes is Amazon Aurora.
Amazon Aurora is a MySQL and PostgreSQL-compatible relational database built for the cloud, designed to provide high performance and scalability. It uses a distributed architecture with multiple instances in separate Availability Zones, allowing it to provide read and write access to all instances. This makes it highly available and suitable for applications that require both read and write operations at scale.