In a room filled with 7 people, 4 people have exactly 1 sibling in the room and 3 people have exactly 2 siblings in the room. If two individuals are selected from the room at random, what is the probability that those two individuals are NOT siblings?  Choices
A) 5/21
B) 3/7
C) 4/7
D) 5/7
E) 16/21
# of selections of 2 out of 7 - C27=21C72=21;   # of selections of 2 people which are not siblings - C12∗C12C21∗C21 (one from first pair of siblings*one from second pair of siblings)+C12∗C13C21∗C31 (one from first pair of siblings*one from triple)+ C1^_2*C^1_3(one from second pair of siblings*one from triple) =4+6+6= 
<gadget id="calculator">4+6+6</gadget>
<output>16</output>
16=4+6+6= 
<gadget id="calculator">4+6+6</gadget>
<output>16</output>
16.   P=16/21   ANSW16/21R:16/21
<result>E</result>
In a room filled with 7 people, 4 people have exactly 1 sibling in the room and 3 people have exactly 2 siblings in the room. If two individuals are selected from the room at random, what is the probability that those two individuals are NOT siblings?