Answer:
The answer is: She wants to share in her daughter’s accomplishments.
Step-by-step explanation:
When you're motivated to introduce someone is because you´re proud of something about them, in this case, the mother is proud about her daughter's accomplishments, and thus that is her motivation for introducing her to everyone. The first option isn't possible as adhering the customs of a community has nothing to do with motivation, the second option isn't possible either as satisfying people's curiosity isn't another way of feeling motivated to do something, and finally the last option is the least possible for exerting control over her won't cause her motivation to introduce to others.