An architecture consists of the following
a)A primary and secondary infrastructure hosted in AWS.
b)Both infrastructures consist of ELB, Autoscaling and EC2 resources.
How should Route53 be configured to ensure proper failover if the primary infrastructure goes down?

Answer options:

A.Configure a primary routing policy.
B.Configure a weighted routing policy.
C.Configure a Multi-Answer routing policy.
D.Configure a failover routing policy.

Answer - D
The AWS Documentation mentions the following.
You can create an active-passive failover configuration by using failover records. You create a primary and a secondary failover record with the same name and type, and you associate a health check with each. 
For more information on DNS failover using Route53, please visit the following URL:
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/dns-failover-configuring-options.html