Final answer:
100°C is the hottest temperature among the given options, as it is equivalent to the boiling point of water (212°F or 373.15K), and it is higher than 100°F and much higher than 100K, which is below the freezing point of water.
Step-by-step explanation:
To determine which temperature is hottest among 100K, 100°F, and 100°C, we need to convert them to the same scale. The boiling point of water is 100°C, which is equivalent to 212°F and 373.15K. Since Kelvin is an absolute scale with no negative values, and 100K is far below the freezing point of water, it is not the hottest. Between 100°F and 100°C, the latter is hotter because it is the boiling point of water, while 100°F is below human body temperature (which is about 37°C or 98.6°F). Therefore, 100°C is the hottest temperature among the given options.