Option 1 -> Obvious means clear and easily understood, which is the opposite of obscure.
Option 2 -> Ambiguous means unclear or having multiple meanings, which is similar to obscure, not opposite.
Option 3 -> Murky means dark or unclear, which is a synonym of obscure, not an antonym.
Option 4 -> Obsolete means outdated or no longer in use, which is unrelated to the meaning of obscure.
Hence, Option 1: Obvious -> "Obscure" means unclear, hidden, or difficult to understand, while "obvious" means clear, evident, and easily perceived, making them perfect antonyms -> correct