求解答

JJessicayang

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?A 5/21
B 3/7
C 4/7
D 5/7
E 16/21



怎么算的啊