AWS Certified Solutions Architect - Professional (#503)

Doug has created a VPC with CIDR in his AWS account. In this VPC he has created a public subnet with CIDR block While launching a new EC2 from the console, he is not able to assign the private IP address to this instance. Which is the most likely reason for this issue?

Private address IP is currently assigned to another interface
Private IP address is reserved by Amazon for IP networking purposes.
Private IP address is blocked via ACLs in Amazon infrastructure as a part of platform security.
Private IP address is not part of the associated subnet's IP address range.