In a story which of these would be the best indicator that a character is protagonist

The answer is "He is motivated to achieve a goal."

The sentence shows the best indicator that a character is protagonist is C. he is motivated to achieve a goal.

Explanation:

In literature, a protagonist is a main character of a literary work that leads the course of the story through his decisions and experiences. As the main character, the protagonist is motivated to achieve a goal and take action in the story, regardless of the possible conflicts or antagonists he or she may need to deal with.