option

1. Contract to keep an offer open for a fixed period during which the offerorcannot withdraw the offer. 
2. Formal Contract between a seller (the optioner) and a buyer (the optionee) the right (but not the obligation) to buy-and-sell (or to buy-or-sell) a specificproperty or a fixed-quantity of a commodity, currency, or security, at a fixed price (called exercise price) on or up to a fixed ...

You must always leave yourself an option as a way out if things do not go well and you need to change your course.