"If compound X is boiling, then its temperature must be at least 150°C." Assuming that this statement is true, which of the following must also be true? a. If the temperature of compound X is at least 150°C, then compound X is boiling. Answer + b. If the temperature of compound X is less than 150°C, then compound X is not boiling. Answer + c. Compound X will boil only if its temperature is at least 150°C. d. If compound X is not boiling, then its temperature is less than 150°C. e. A necessary condition for compound X to boil is that its temperature be at least 150°C. f. A sufficient condition for compound X to boil is that its temperature be at least 150°C.