Ruby's Laundry Room Needed Cleaning

Ruby's laundry room needed cleaning. She promised her seventeen year-old daughter Pearl that if she cleaned the laundry room, she would pay her $50. Which statement is TRUE?​

A) Pearl is obligated to perform under an express bilateral agreement and Ruby is obligated to pay.
B) This is an example of a unilateral contract and Pearl is under no obligation to perform, but if she does, she is entitled to $50.
C) This is an example of a quasi contract, and if Pearl cleans, she would be entitled to the value of her services, which may or may not be $50.
D) There is no consideration so no contract.