Regarding the attaching of ENI to an instance, what does 'warm attach' refer to?

Regarding the attaching of ENI to an instance, what does ‘warm attach’ refer to?

Regarding the attaching of ENI to an instance, what does ‘warm attach’ refer to?
A . Attaching an ENI to an instance when it is stopped.
B . This question doesn’t make sense.
C . Attaching an ENI to an instance when it is running
D . Attaching an ENI to an instance during the launch process

Answer: A