In the data set shown below, what is the value of the quartiles?
{56, 58, 64, 68, 72, 75, 78}
A. Q1 = 58; Q2 = 68; Q3 = 73.5
B. Q1 = 61; Q2 = 68; Q3 = 73.5
C. Q1 = 75; Q2 = 68; Q3 = 58
D. Q1 = 58; Q2 = 68; Q3 = 75