Your burger is done at __ 21^circ C(72^circ F) 41^circ C(106^circ F) 71^circ C(160^circ F) a quarter to one

The correct answer is . This is the recommended internal temperature for cooked ground beef to ensure it's safe to eat. The other temperatures are too low and could allow harmful bacteria to survive. "A quarter to one" refers to a time, not a temperature.