The temperature in a laboratory must be between 68 and 74 fahrenheit, inclusive. if t is the temperature in the laboratory, which of the following inequalities represents this situation?

The midpoint between 68 and 74 degrees is 71. T is unknown, so unknown minus midpoint is 71-t, but it has to be positive so it's written as | 71-t |. 74-71 = 3 and 71-68= 3, which means the temps CAN NOT fluctuate more than 3 degrees. Using that information, I believe that the correct answer is:
B) | 71-t |  3