The course says "Aurora PostgreSQL does not support cross-region replicas at present", but https://aws.amazon.com/rds/aurora/faqs/ says it can, unless if I am reading wrong. Excerpt below:
Q: Can I have cross-region replicas with Amazon Aurora?
Yes, you can set up cross-region Aurora replicas using either physical or logical replication.
Physical replication, called Aurora Global Database, uses dedicated infrastructure that leaves your databases entirely available to serve your application, and can replicate to up to five secondary regions with typical latency of under a second. It’s available for both Aurora MySQL and Aurora PostgreSQL
Yes, AWS introduced this cross-region capability in March 2020 so we will need to update that quiz question.