Ash and Rachel Are Sisters

Ash and Rachel are sisters.They agree to go on holiday together to Tasmania the following month.A week later Rachel tells Ash she wants to go by herself.Ash accuses Rachel of breaching their contract.Which of the following is true?

A) There is no contract because their agreement was not in writing.
B) There is a valid contract that has been breached by Rachel.
C) There is no contract because the parties will be assumed to have lacked the intention to be legally bound.
D) There is no contract because there is no agreement.