When Brianna tries to start her new car and the motor stalls, she gets out of her car and screams that she will sell the car to anyone for $10. Nelly, a passerby who owns Nelly's Used Cars, hands Brianna $10. This is

a. not a valid acceptance because Brianna does not seriously intend to sell.

b. a valid acceptance because Nelly is a professional dealer.

c. not a valid acceptance because Nelly is only passing by.

d. a valid acceptance because Brianna is seriously frustrated.