Answer: B) Scaffolding
Step-by-step explanation:
Scaffolding is defined as educating technique in which a person is made to learn a process by moderately shedding the external help and support. It can be used for solving academic problems,learning any process, building, driving etc.
According to the question, Janet's father is using scaffolding technique to teach bicycle riding to Janet.He is withdrawing his assistance at gradual times to let her learn on her own and help her at the time if she finds any difficulty in riding.
Other options are incorrect because fast mapping is learning about new things by low exposure. Rehearsal is practicing things through repeating the act.Contrast assumptions are one label persisting assumptions.Thus, the correct option is option(B).