You have launched an RDS instance in your VPC. The endpoint that is assigned to your DB instance is a long, partially random, alphanumeric string, for example, myexampledb.a1b2c3d4wxyz.us-west-2.rds.amazonaws.com. Your organization wants to use a name that`s easier to remember. So you registered a domain name using the Route53 service. Which type of record set do you need to create?

Answer options:

A.A - IPv4 Address with Alias=NO
B.A - IPv4 Address with Alias=YES
C.CNAME - Canonical Name with ALIAS=NO
D.CNAME - Canonical Name with ALIAS=YES

Answer: C
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-to-rds-db.html
Note:
A Record (Address Record) is typically used when an IP address to name conversion is required. This is most commonly used. 
A record points a name to specific IP. If you want tests.com to point to the server 10.120.13.14, you will configure an A record.
tests.com A 10.120.13.14
A CNAME record (Canonical record) points a name to another name. Typically a complex name with alphanumeric characters can be shortened to a user understandable format.
blog.tests.com CNAMEblog235_github_repoABCD.io.net
In the question, the AWS generated resource name is complex i.e myexambledb.a1b2c3d4.......
This can be converted to a user-friendly name by using a CNAME record.