Which of the Following Couples Is MOST Likely to Be

Which of the following couples is MOST likely to be perceived as having hooked up?

A) Chris,who flirtatiously touches Jenny soon after first meeting her in the hallway of his fraternity's house.
B) Elise and Matt,who,after having been dating for three months,spend their first night together.
C) Kevin and Harrison,who,after working on their science lab report all evening,eventually engage in sexual activity;the next day,they agree to just be friends with benefits.
D) Sally and Samantha have been best friends since preschool,they sometimes try kissing to see what it feels like and practice for their future romantic relationships.