Option (a) is correct because the speaker's tone is appreciative and optimistic. The speaker is appreciative as they praise the 'extraordinary ability' of the Paralympics and admire the 'strength, skill, and competitive spirit' of the para-athletes. The tone is optimistic because the speaker focuses on positive changes and a hopeful future, noting that the Paralympics 'breaks down preconceived notions' and has 'given me a new lease of life and helped me push boundaries.' The tone is not moralistic, sentimental, or defensive.