Can one instance be registered with two ELBs in the same region?

A.
No

B.
Yes, provided both ELBs have the same health check configuration

C.
Yes, always

D.
Yes, provided both ELBs are in the same AZ

Explanation:
Yes, it is possible to have one instance part of two separate ELBs, though both ELBs have different configurations. ELBs
are never launched in specific zones.
http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/enable-disable-az.html