To find these values, you must first order the data from least to greatest.
26, 28, 28, 33, 34, 36, 39, 42, 48
The maximum is the greatest: 48.
The minimum is the least: 26.
Q2 is the middle value when in order: 34.
Q1 is the middle value of the lower half: 26, 28, 28, 33; (28 + 28)/2 = 28.
Q3 is the middle value of the upper half: 36, 39, 42, 48; (39 + 42)/2 = 40.5.
The correct answer is the first choice.