You are appointed as Cloud Consultant in a Cloud Solutions Firm. They have the following VPCs set up in the US East Region: The first VPC with CIDR block 172.10.0.0/16 having a subnet with CIDR block 172.10.10.0/24. The second VPC with CIDR block 192.168.0.0/16, having a subnet with CIDR block 192.168.20.0/24. Your colleague is trying to establish a network connection between two subnets, a subnet with CIDR block 172.10.10.0/24 and another subnet with CIDR block 192.168.20.0/24. Also, they don’t want any transitive peering relationship. The connection should not have a single point of failure for communication or a bandwidth bottleneck. Which of the following is the easiest solution?

Answer options:

A.Use VPC Peering i.e. AWS-provided network connectivity between two VPCs.
B.Use Software VPN i.e. Software appliance to VPN connection between VPCs.
C.Use VPC-to-VPC routing over IPsec VPN connection.
D.VPC-to-VPC routing in an AWS Direct Connect location.

Correct Answer - A
Option A is CORRECT because VPC Peering uses the existing infrastructure of a VPC and this solution is straightforward that facilitates the transfer of data between two VPCs. 
Options B, C, and D are incorrect because they are not the easiest solution or may be a single point of failure for the connections.
Refer: https://docs.aws.amazon.com/vpc/latest/peering/what-is-vpc-peering.html