Which one of the following is the lowest possible temperature?

The lowest possible temperature is known as absolute zero, which represents the theoretical point where all molecular movement stops and a system has zero thermal energy. By international agreement, absolute zero is defined as 0 Kelvin (0 K) on the thermodynamic scale, which corresponds to -273.15° Celsius. This value was historically derived by extrapolating the ideal gas law, suggesting that the volume of a gas would theoretically reach zero at approximately -273.15° Celsius. While scientists have achieved temperatures extremely close to this limit, such as 700 nK, absolute zero itself remains a theoretical minimum where matter reaches its ground state and entropy is at its minimum value. Among the given options, -273° Celsius is the closest integer representation of this fundamental physical limit.