Given the choices, "happy" is the least bad answer. "Happy" is not a good opposite for "uneasy". Suitable choices would be: "relaxed" "at ease" "calm" "composed" The test question is poorly conceived.

"eased" isn't opposite of "uneasy"

The word "eased" means to move carefully or gradually, for example: "I eased off my shoes" (I took my shoes off slowly and carefully). To use a word or phrase which sounds similar to describe the opposite of "uneasy", I could say that "I feel at ease", for example. But as "at ease" isn't an option in the exercise, the best option here is "happy".

The BEST answer is HAPPY... but I agree with the others that the opposite of UNEASY is not HAPPY! Yesterday I EASED OFF my shoes and put my feet up. = slowly, gently removed The aspirin tablet EASED my pain. = lessened/reduced pain Tensions have EASED between them. = lessened/reduced problems The traffic has EASED OFF. = less traffic = less problem. It definitely cannot be used as an opposite of UNEASY.