Final answer:
Henrietta showed she was growing up by offering strategic advice.
Step-by-step explanation:
The correct answer is c) She began offering strategic advice. Kelly Marie and Brendan noticed that Henrietta was growing up because she started offering strategic advice. This shows that she was becoming more mature and capable of thinking critically and providing guidance. Examples of strategic advice could include suggesting different tactics or approaches during games or offering suggestions on how to improve gameplay. This development indicates that Henrietta was becoming a more active and valuable participant in the games.