A Company Is Concerned That Two NAT Instances in Use

A company is concerned that two NAT instances in use will no longer be able to support the traffic needed for the company's application. A solutions architect wants to implement a solution that is highly available fault tolerant, and automatically scalable. What should the solutions architect recommend?

A) Remove the two NAT instances and replace them with two NAT gateways in the same Availability Zone.
B) Use Auto Scaling groups with Network Load Balancers for the NAT instances in different Availability Zones.
C) Remove the two NAT instances and replace them with two NAT gateways in different Availability Zones.
D) Replace the two NAT instances with Spot Instances in different Availability Zones and deploy a Network Load Balancer.