A user has created an ELB with three instances. How many security groups will ELB create by default?

A.
3

B.
5

C.
2

D.
1

Explanation:
Elastic Load Balancing provides a special Amazon EC2 source security group that the user can use to ensure
that back-end EC2 instances receive traffic only from Elastic Load Balancing. This feature needs two security
groups: the source security group and a security group that defines the ingress rules for the back-end
instances. To ensure that traffic only flows between the load balancer and the back-end instances, the user
can add or modify a rule to the back-end security group which can limit the ingress traffic. Thus, it can come
only from the source security group provided by Elastic load Balancing.