Which of the following is the best example of the synchrony of behaviours that underlies the development of an attachment relationship? a) Dr. Hall rocked, read stories, and sang to her infant son until they were both drowsy. b) c) d) Six-month-old Jarod and his mother have a conversation in which she imitates his babbling and he seems to imitate what she is saying. Kenny and Carrie shared toys and tasks to build a sand fort in the sandbox. When Jeremy and Amanda refused to be satisfied with separate toys, they were each given 30 minutes in time out.