An American put with strike $15 is not at expiry and the underlying asset is worth $10. A holder of this put might: O not exercise the option because the option is worthless at this time. O do nothing because the option cannot be exercised until expiry. O do nothing because it's the writer who decides when to exercise an option. O consider exercising the option to sell the underlying asset for $15. O consider exercising the option to buy the underlying asset for $10.