Which Men's u20 has a Men's 45 of n/A?
CREATE TABLE table_46943 (
    "Year" real,
    "Men's Open" text,
    "Women's Open" text,
    "Mixed Open" text,
    "Men's u20" text,
    "Women's u20" text,
    "Senior Mixed" text,
    "Men's 30" text,
    "Women's 30" text,
    "Men's 35" text,
    "Women's 35" text,
    "Men's 40" text,
    "Women's 40" text,
    "Men's 45" text,
    "Men's 50" text
)
SELECT "Men's u20" FROM table_46943 WHERE "Men's 45" = 'n/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 Men's u20 has a Men's 45 of n/A? ### Input: CREATE TABLE table_46943 (
    "Year" real,
    "Men's Open" text,
    "Women's Open" text,
    "Mixed Open" text,
    "Men's u20" text,
    "Women's u20" text,
    "Senior Mixed" text,
    "Men's 30" text,
    "Women's 30" text,
    "Men's 35" text,
    "Women's 35" text,
    "Men's 40" text,
    "Women's 40" text,
    "Men's 45" text,
    "Men's 50" text
) ### Response: SELECT "Men's u20" FROM table_46943 WHERE "Men's 45" = 'n/a'