user: Question: What was the tier versus Annalisa Bona?
Columns: ['Date', 'Tournament', 'Surface', 'Tier', 'Opponent in the final', 'Score']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['September 15, 2002', 'Sofia', 'Clay', 'ITF $25k', 'Desislava Topalova', '6–3, 4–6, 6–0']
SQL:

assistant: SELECT "Tier" FROM "Table" WHERE "Opponent in the final" = 'Annalisa Bona';