One ton of refrigeration is defined as the rate of heat transfer needed to melt one ton of ice in 24 hours, which equals 12,000 BTU/hour. Converting to kilowatts: 12,000 BTU/hr ÷ 3412.142 BTU/hr/kW = 3.516 kW. The option '3.6 kw/s' (likely meaning kW) is the closest approximation among the choices, though 3.5 kW would be more precise.