Concept:An antonym is a word opposite in meaning.
Accidentally means by chance, without meaning to do it.
Solution:The opposite of doing something by accident is doing it on purpose, that is,
intentionally.
"Willingly" means readily or without being forced; it is about agreement, not purpose, so it is not the exact opposite.
"Carelessly" and "foolishly" describe how an accident may happen; they are not opposites of
accidentally.
Key point: The stored key gave (C) carelessly, which is close to the meaning of the word, not its opposite. The opposite of
accidentally is
intentionally (deliberately).
Answer:Option A (intentionally)