Answer:
A) if it is deemed a necessary good
Step-by-step explanation:
Minors are not usually bound by a contract, and most of the time they can avoid liability under a contract. Minors can only sign a valid contract if it includes something that is essential for them. Medicines, food and medical services are the only things that are usually considered essential for a minor.
So the store has to prove that selling her the cell phone was a necessity, and something essential for her. It is possible to prove that it was a necessity, but it is something very difficult to do.
But the fact that the contract is not valid doesn't mean that Lydia can do whatever she wants. Her parents are responsible for returning the cell phone or since she lost it, they are responsible for paying it.