You have created an Application Load Balancer. You need to point your domain names of www.example.com and example.com to the Application Load Balancer. Your Hosted zone is example.com. How can you achieve this?
 

Answer options:

A.Create one CNAME record for the ALB to www.example.com. and then create another CNAME record to the ALB to example.com
B.Create an Alias record, for example.com and point it to the ALB as the target. Create a CNAME record for www.example.com and point it to example.com
C.Create an ALIAS record for the ALB and point it to example.com. Create a PTR record for www.example.com and point it to example.com
D.Create one CNAME record for the ALB to www.example.com. and then create another PTR record to the ALB to example.com

Answer – B
The AWS Documentation mentions below on ALIAS records which can be created.
Choosing Between Alias and Non-Alias Records
Amazon Route 53 alias records provide a Route 53–specific extension to DNS functionality. Alias records let you route traffic to selected AWS resources, such as CloudFront distributions and Amazon S3 bucket. They also let you route traffic from one record in a hosted zone to another record.
Unlike a CNAME record, you can create an alias record at the top node of a DNS namespace known as the zone apex. For example, if you register the DNS name example.com, the zone apex is example.com. You can`t create a CNAME record for example.com. But you can create an alias record for example.com that routes traffic to www.example.com.
When Route 53 receives a DNS query for an alias record, Route 53 responds with the applicable value for that resource:
A CloudFront distribution – Route 53 responds with one or more IP addresses for CloudFront edge servers that can serve your content.
An Elastic Beanstalk environment – Route 53 responds with one or more IP addresses for the environment.
An ELB load balancer – Route 53 responds with one or more IP addresses for the load balancer.
An Amazon S3 bucket configured as a static website – Route 53 responds with one IP address for the Amazon S3 bucket.
Another Route 53 record in the same hosted zone – Route 53 responds as if the query is for the record referenced by the alias record.
You can then create a CNAME record for www.example.com.
Option A is incorrect because you cannot create a CNAME record at the zone apex.
Options C and D are incorrect since PTR records cannot be used.
For more information on alias and non-alias records, please refer to the below URL
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/resource-record-sets-choosing-alias-non-alias.html