Jasper works as a pizza chef. He preheats the pizza oven, and the function (T(m)) represents the oven's interior temperature, in °F, after (m) minutes of preheating. What is the range of (T(m))?
a) All real numbers greater than or equal to 72°F
b) All real numbers greater than or equal to 0°F
c) All real numbers between 0°F and 72°F
d) All real numbers between 72°F and 84°F