Which of the following is a complex sentence? (1 point)

The family made sure they packed warm clothes before their trip up
north.
○ Her brother said they would be boring, but he absolutely loved them.
Ellie had been to the mountains, but her brother had never seen
them.
Ellie wants to go back and eventually live in the mountains someday.

Ellie had been to the mountains, but her brother had never seen them.