Which 1991 has an A 1993 ?
CREATE TABLE table_36304 (
    "Tournament" text,
    "1988" text,
    "1989" text,
    "1990" text,
    "1991" text,
    "1992" text,
    "1993" text,
    "1994" text,
    "1995" text,
    "1996" text,
    "1997" text,
    "1998" text
)
SELECT "1991" FROM table_36304 WHERE "1993" = 'a'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: Which 1991 has an A 1993 ? ### Input: CREATE TABLE table_36304 (
    "Tournament" text,
    "1988" text,
    "1989" text,
    "1990" text,
    "1991" text,
    "1992" text,
    "1993" text,
    "1994" text,
    "1995" text,
    "1996" text,
    "1997" text,
    "1998" text
) ### Response: SELECT "1991" FROM table_36304 WHERE "1993" = 'a'