Sarah Finds That Her Son James Enjoys Lemon Candy

Sarah finds that her son James enjoys lemon candy.Sarah reinforces James when he displays courteous behaviour at home.She then starts to reinforce this behaviour at school,relatives' homes,and church.What type of study design did Sarah employ?

A) Across situations multiple baseline design
B) Across behaviours multiple baseline design
C) Across subjects multiple baseline design
D) ABA design