Hi Anusha,

Simple event or single events are like Tossing a single  coin or rolling a single die or picking a ball from pool of balls etc.

Complex event is nothing but product of simple events. Like tossing a coin 2 or more times or rolling a die more than once or picking more than a ball from a bag of balls etc.

Independent event: One event does not impact on other. Or else, as far as GMAT is concerned look for the word “replaced” in the question, if its given then its a independent event because denominator wont change(total number of outcomes).

Dependent event: An event has an impact on other event. Or else, as far as GMAT is concerned if they have not mentioned”replaced” in the question, then its a dependent event because denominator changes for every simple event(total number of outcomes).

So here in this question, we have to pick 2 pens which not defective.

9 are not defective.

So, first time when we pick a not defective pen, the probability is 9 /12

second time it is 8/ 11.

So, 9/ 12  * 8/11 = 6/11.

So the answer is C.

Hope this helps.