In 50 to 100 words, list three ways through which an author can show character development.

Keep in mind your character's background, and motivations. A character without motivations makes a poor plot, but more importantly character motivations are key to developing the character throughout the plot. What motivates your character? What are his wants and needs?
If the character is voluntarily doing something, why is he or she doing it? An example of this would be Suzanne Collins's Hunger Games when Katniss volunteered herself to the games so her sister wouldn't have to. She did this because she loved her sister. 
Hope this helps!