Explanation:

- The phrase "at a disadvantage" means being in a less favorable position. The antonym would mean being in a favorable or superior position.

- Option 1: powered – This doesn't directly contradict being at a disadvantage, as being powered doesn't imply an advantage or superior position.

- Option 2: privileged – This means having a special right or advantage. This is the opposite of being at a disadvantage.

- Option 3: useless – This doesn't relate to having an advantage or disadvantage. It describes a lack of utility or function.

- Option 4: unhappy – This describes an emotional state and doesn't relate to being at a disadvantage or advantage.