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Out of 4 people, why does ways to choose a 2-person committee overcount by 2 the ways to divide the 4 into 2 teams of 2?

1. Please see the sentence alongside my red line below.  Why does part (a) overcount part (b) by a factor of c? 

2. Scilicet, why aren't the answers to parts (a) and (b) the same? Whenever you choose a 2-person committee #1, the remaining unchosen 2 members automatically can form the 2-person committee #2. 

3. Thus where's the overcounting? 

>![](https://i.imgur.com/EkPQYG7.jpg)

Blitzstein. *Introduction to Probability* (2019 2 ed). p. 15.