Subject: mathqa
Question: in a box of 9 pens , a total of 2 are defective . if a customer buys 2 pens selected at random from the box , what is the probability that neither pen will be defective ?
Option: 
A: 5 / 9
B: 4 / 7
C: 8 / 15
D: 7 / 12
Answer: D