Correct option is C
The correct answer for the temperature at which milk is heated in the pasteurization method for 15 to 30 seconds to kill microbes is (c) 70°C
This process, often referred to as High Temperature Short Time (HTST) pasteurization, typically involves heating the milk to about 72°C for at least 15 seconds, but 70°C for 15 to 30 seconds is a commonly used approximation in some contexts.