Which solution should the SysOps administrator implement to meet these requirements?

Explanations:

Adding a second EC2 instance as a read replica does not provide high availability for write-intensive workloads, nor does it provide automatic failover or scalability in a multi-tenant scenario.

Migrating to Amazon Aurora and adding an Aurora Replica is a good option for read scalability, but it does not meet the requirement for high availability in write-intensive workloads with multi-tenancy.

Migrating to an Amazon Aurora multi-master DB cluster allows for high availability and supports write operations across multiple nodes. This solution is ideal for write-intensive workloads and multi-tenant scenarios, as it can handle writes at scale and provide failover capabilities.

Migrating to Amazon RDS for MySQL does provide managed database services but does not offer the same level of write scalability and high availability features as Aurora, particularly in multi-tenant, write-intensive environments.