A Lambda worker must never exceed 20 concurrent invocations because its database has limited capacity. It does not require preinitialized environments. Which configuration directly enforces this limit?

1. Set provisioned concurrency to 20 and assume it is a hard maximum.
2. Increase the function timeout to 20 minutes.
3. Set the batch size to 20 for every possible invocation source.
4. Set reserved concurrency to 20 for the function.