Option 1 -> Fickle means changeable or inconstant, which is actually a synonym of capricious, not an antonym.
Option 2 -> Incongruous means out of place or incompatible, which is unrelated to the meaning of capricious.
Option 3 -> Inconsistent means not staying the same, which is also a synonym of capricious, not an antonym.
Option 4 -> Steadfast means firm, unwavering, and constant, which is the direct opposite of capricious.
Hence, Option 4: Steadfast -> Capricious means unpredictable and subject to sudden changes, while steadfast means firm and unchanging in attitude or purpose, making them perfect antonyms -> correct