Final answer:
The scenario describing Jayce starting to crawl exemplifies a key developmental milestone that is associated with the timing of attachment formation in infants, revealing the relationship between increased mobility, exploration, and the enhancement of the attachment bond.
Step-by-step explanation:
The scenario that exemplifies a key factor in predicting the timing of attachment in infants is "Jayce is starting to crawl." The ability to crawl indicates a developmental milestone where the infant is beginning to explore their environment, which correlates with the development of secure attachment as the infant starts to use the caregiver as a secure base. According to developmental theories and research, as infants gain mobility and cognitive milestones such as object permanence, they also begin to develop stronger attachments, showing preferences for familiar caregivers and possibly displaying stranger anxiety. Motor skills such as crawling allow the infant to return to the caregiver after exploring, which reinforces the attachment bond.