Option 1 -> unchecked - This is a synonym of rampant, meaning uncontrolled or unrestricted.
Option 2 -> restrained - This means controlled or limited, which is the opposite of rampant (uncontrolled/widespread).
Option 3 -> widespread - This is a synonym of rampant, meaning occurring extensively.
Option 4 -> inordinate - This means excessive or unreasonable, which is similar to rampant.
Hence, Option 2: restrained -> "Rampant" means uncontrolled or spreading unchecked, while "restrained" means controlled or held back, making them antonyms -> correct