Final answer:
Oxytocin is known for its role in childbirth, lactation, and bonding, but its effect on bonding is not universally 'always'; it is context-dependent. Thus, the statement that oxytocin always increases bonding would be incorrect.
Step-by-step explanation:
The hormone oxytocin has been associated with various physiological processes, including childbirth and lactation, as well as social functions like bonding and the reinforcement of social ties. Oxytocin's role in bonding, specifically, is complex and context-dependent rather than absolute. It is known to increase feelings of love and closeness in certain situations but does not lead to increased bonding universally 'always' or in every context. Therefore, the correct completion of the sentence, 'Oxytocin increases bonding and ______ always,' would be option 2) 'never' as it is not correct to state that oxytocin always increases bonding without exception.