Answer
Imitating her vocal and facial expressions.
Explanation
Synchrony encompasses both the mother's and the child's responsivity and their emotional capacity to respond each other.For Victor and Rosa want to enhance their synchrony with their 6-month-old daughter they need to match their behaviors, emotional states and biological rhythms between them as parents and the infants because together that forms a single relational unit.The best thing they can do is by Imitating her vocal and facial expressions.
