Your answers should make reference to cases and statutory provisions where relevant.

Kenny buys a mobile phone from Carol at the asking price of $300. Kenny pays Carol $300 and takes possession of the mobile phone. When Carol later discovers the mobile phone could have been sold at a higher price, she demands Kenny to return the mobile phone. Based on the scenario, what is the consideration? Is Kenny under any obligation to return the mobile phone to Carol? Can Carol argue that consideration needs to be equal to the market value before it is considered valid?