To determine the correct answer, let's examine the scenario: a family has two children and we want to find the cases where there are fewer boys (b) than girls (g).
Let's consider all possible combinations of boys and girls in the family, which are represented as:
- bb (both children are boys)
- bg (first child is a boy, second child is a girl)
- gb (first child is a girl, second child is a boy)
- gg (both children are girls)
We are specifically looking for situations where there are fewer boys than girls.
By examining each possibility:
- In "bb," there are 2 boys and 0 girls.
- In "bg," there is 1 boy and 1 girl.
- In "gb," there is 1 boy and 1 girl.
- In "gg," there are 0 boys and 2 girls.
Only one outcome, "gg," has fewer boys than girls (0 boys and 2 girls).
Thus, the correct answer is:
```
gg
```
So, the correct option is:
OD. bb