Answer:
Option D, Successive Approximations
Step-by-step explanation:
Successive approximation are series of rewards given to an individual to positively reinforce the behavioral changes in an individual in order to motivate him /her to move towards achieving the final desired behaviour.
In case if Michelle give rewards to her daughter at each steps of the toilet training activity, then she will be inspired/motivated to do her task efficiently and faster.
Hence, option D is correct.