You are building a deployment system on AWS. You will deploy new code by bootstrapping instances in a private subnet in a VPC at runtime using UserData scripts pointing to an S3 zip file object, where your code is stored. An ELB in a public subnet has network interfaces and connectivity to the instances. Requests from users of the system are routed to the ELB via a Route53 A Record Alias. You do not use any VPC endpoints.
Which is a risk of using this approach?

A. Route53 Alias records do not always update dynamically with ELB network changes after deploys.
B. If the NAT routing for the private subnet fails, deployments fail.
C. Kernel changes to the base AMI may render the code inoperable.
D. The instances cannot be in a private subnet if the ELB is in a public one.