The correct answer to the question is option 1, exposing the affected person to fresh oxygen. Carbon monoxide poisoning occurs when a person inhales carbon monoxide gas, which interferes with the ability of red blood cells to transport oxygen. The lack of oxygen can be life-threatening and requires immediate medical attention. Exposing the affected person to fresh oxygen helps to increase the oxygen levels in their blood, which helps to remove the carbon monoxide gas. This can be done by using an oxygen mask or taking the person to an area with fresh air. Options 2, 3, and 4 (eating butter, drinking lemon-water, and consuming a multi-vitamin tablet) do not directly address the underlying issue of carbon monoxide poisoning and are not effective in treating this condition.