Final answer:
The correct word to complete the sentence is complacent. Growing complacent would mean becoming too comfortable and not actively protecting the freedoms and rights that a free people enjoy.
Step-by-step explanation:
The correct word to complete the sentence is complacent. A free people cannot afford to grow complacent but must remain ever vigilant in safeguarding their liberties.
Being complacent means being satisfied or content with the current situation and not making an effort to make changes or improve.
In the context of the sentence, growing complacent would mean becoming too comfortable and not actively protecting the freedoms and rights that a free people enjoy.