A.I. Explanation:

Option 1: "Because it is inherent and cannot be changed."

Explanation: This option is incorrect because the speaker emphasizes that self-confidence is a skill that can be trained, not something inherent or unchangeable. The text states, 'I use the word skill because I believe it can be trained,' which directly contradicts the idea that it cannot be changed.

Option 2: "Because it is necessary only for soccer players."

Explanation: This option is incorrect as it misrepresents the speaker's point. The speaker discusses self-confidence in the context of soccer but does not limit its necessity to soccer players alone. Self-confidence is portrayed as a universal skill applicable to various tasks, not just soccer.

Option 3: "Because it can be trained and developed."

Explanation: This option is correct because the speaker explicitly states that self-confidence is a skill that can be trained. The phrase 'I believe it can be trained' supports this answer, indicating that self-confidence is not fixed but can be improved through effort and practice.

Option 4: "Because it requires no effort to maintain."

Explanation: This option is incorrect as it contradicts the speaker's message. The speaker implies that building self-confidence requires effort, stating, 'There's no magic button,' which suggests that maintaining self-confidence is not effortless and requires active engagement.