What is the air date for the episode with production code ad1c13?
CREATE TABLE table_53990 (
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "Production code" text
)
SELECT "Original air date" FROM table_53990 WHERE "Production code" = 'ad1c13'
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: What is the air date for the episode with production code ad1c13? ### Input: CREATE TABLE table_53990 (
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "Production code" text
) ### Response: SELECT "Original air date" FROM table_53990 WHERE "Production code" = 'ad1c13'