Cognitive scientists consider listening to be a process that includes:

Selection Organization Integration
Selection includes Attention or perception. Numerous messages, at any given one time, compete for our attention. Whether it is words spoken by a lecturer or events occurring around us, whatever the origin of the stimuli, humans cannot simply focus on all of them at once. Therefore, we must choose, consciously or unconsciously, to reject some stimuli or attend to others.
Organization which includes interpretation. This is the combination of visual and auditory information that we receive and attempt to make meaning out of it. This component engages cognitive processing as we take in relational and contextual cues and try and connect them in meaningful ways to past experiences.
Integration which includes storage recall. In terms of capacity, humans can hold a huge amounts of unsorted auditory info for up to 4 seconds. As stimuli are interpreted and organized, they make their way to short memory where they are forgotten or transferred to long term memory. 

Ithink it's a, but i might be wrong