What is the key character's challenge?

what does this question mean?

What is the difference between a major and a minor character? a major character has a less important story line, while a minor character plays a bigger role in the plot. a major character plays a big role in the plot, while a minor character has a less important story line. a major character has an unimportant story line in the plot. a minor character's story line is as important and developed as the major characters' story lines.

In these frames, the author emphasize the challenges lqbal faced by showing

How does the mother defend her child to the old duck