Final answer:
Active involvement is the stage in the listening process where one pays close attention to both verbal and nonverbal cues to fully understand and engage with the speaker.
Step-by-step explanation:
During the listening process, it is during the active involvement stage, option (a), when a listener pays close attention to verbal and nonverbal signals. This stage is critical because it is when the listener is fully engaged in the communication process, being attentive to the speaker's words as well as to the speaker's body language and other nonverbal cues. This engagement helps in understanding not just the content of what is being said, but also the underlying emotions and intentions. Being attentive to these signals is essential for building rapport and effectively participating in discussions.