Knowing that you find algebra more difficult than your sister does, but that you could improve with practice, is an example of:

Knowing that algebra is harder for you than for your sister, yet improvable with practice, is metacognition.

Self-regulation (A) is managing one's own actions and effort, not knowing about one's thinking.

Self-discipline (C) is controlling impulses to stay on task, not awareness of ability.

Automation (D) is a skill becoming effortless through practice, not self-knowledge.

Metacognition is thinking about one's own thinking and knowing about one's knowing.

John Flavell introduced the term metacognition in the 1970s.