The scenario says that it has a read–intensive MySQL database. This is the reason why we have to use Aurora Read Replicas. To ensure high availability, we have to use an AWS Aurora Cluster.
In RDS, you have to manually configure a Multi-AZ deployments configuration to improve the availability of your database. For an Aurora cluster, it is already high-available by default. Remember that an Amazon Aurora DB cluster consists of one or more DB instances and a cluster volume that manages the data for those DB instances. This is somewhat akin to the Multi-AZ setting in RDS.
For more information about Aurora DB clusters, please check this reference:
Although configuring cross-region replication would improve the availability of the database, this setting is only warranted if you have a disaster recovery plan that covers an outage of the entire AWS region. The use of the Amazon Aurora DB cluster should suffice based on the requirement provided in the scenario.
Hence, the two provided answers are indeed correct.