Here are the options filled in:

1. **vital** - "Friendship is a **vital** part of a teenager's life."
2. **support** - "Friends provide **support** and companionship during a time of many changes."
3. **free** - "Many teenagers enjoy spending time with friends at school and in their **free** time."
4. **together** - "They might hang out at the park, play video games, or go to the movies **together**."
5. **difficult** - "Good friends help each other through **difficult** situations."
6. **stressed** - "When a teenager is feeling down or **stressed**, a supportive friend can make a big difference."

So, the final text would be:

"The Importance of Friendship
Friendship is a **vital** part of a teenager's life. Friends provide **support** and companionship during a time of many changes. Many teenagers enjoy spending time with friends at school and in their **free** time. They might hang out at the park, play video games, or go to the movies **together**. Good friends help each other through **difficult** situations. When a teenager is feeling down or **stressed**, a supportive friend can make a big difference."