Mark the correct alternative in the following:

A lady gives a dinner party for six guests. The number of ways in which they may be selected from among tem friends if two of the friends will not attend the party together is


Suppose there are two friends, A and B, who do not attend the party together.


If both of them do not attend the party, then the number of ways selecting 6 guests = 8C6 = 28


If one of them attends the party, then the number of ways of selecting 6 guests = 2 8C5 = 112


Total number of ways = 112 + 28 = 140

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