In combination problems and PS problems in general it is best if we figure out a method before jumping onto the solution, and also one has to be careful if the problem entails only selection or both selection and arrangement.
Here, we have to select 6 people out of: 2 bachelors and 3 married couples.
The number of ways of selecting any 6 people out of 8 is 8*7*6! /6!*2! = 28
the people will get selected in various ways:-
1. Three couples
2. Two couples, one from 3rd couple and one bachelor
3. One couple, two from two different couples and two bachelors
4. Two couples and two bachelors
Now at this stage we can apply two methods, either we can count the individual cases or we can simply subtract case 1 from total of 28 as out of all these cases, only the first one, which includes three couples, has more than two married couple.
Since GMAT requires us to find the most efficient way to answer a question, let’s go via subtraction;
How many different committees can be formed such that there are 3 couples?
It will be equal to 3 choose 3 i.e. 1 way of selection.
Number of different committees of 6 people such that there are at most two married couple = 28-1=27.
ANSWER IS D.