The density of water is maximum at 4 °C (A). At this temperature, water molecules arrange themselves in a highly ordered structure due to hydrogen bonding. This arrangement allows for the closest packing of molecules, resulting in the highest density. As the temperature deviates from 4 °C, the density of water decreases. Options (B), (C), and (D) are incorrect. Kelvin temperature (K) is an absolute scale, where 4 K is equivalent to -269.15 °C, far below the maximum density temperature of water. Fahrenheit temperature (°F) is a different scale, not relevant to the maximum density of water. Option (D) represents a negative temperature, which is not meaningful in this context. Therefore, the correct option is (A) 4 °C, as it corresponds to the temperature at which water exhibits its maximum density due to the specific arrangement of its molecules.