Sonia Goes to Have Her Hair Trimmed and Agrees to Pay

Sonia goes to have her hair trimmed and agrees to pay $40 to the stylist. While there, Sonia decides that she would also like highlights. The stylist informs her that highlights will cost an additional $30. Sonia agrees to the price, gets the highlights, but refuses to pay the extra amount. What is the likely result in a dispute between Sonia and the stylist and why?

A) The stylist will win because she did additional work in exchange for the extra payment; and, therefore, Sonia's promise was supported by valid consideration.
B) The stylist will win because she did additional work in exchange for the extra payment; and, therefore, a valid unilateral contract existed.
C) The stylist will win unless Sonia can show that she had previously received both a trim and highlights for $40. If she can prove that she previously received both for $40, then the past expectations rule applies.
D) Sonia will win because the stylist had a preexisting duty to have Sonia's hair look as good as possible.
E) Sonia will win because there was no valid consideration in exchange for the highlighting.