6510. There was nothing casual about my father’s interests.

✅ The correct answer is option A.
Ordinary : with no special or distinctive features; normal.

Incidental : happening as a minor accompaniment to something else.

Funny : causing laughter or amusement; humorous.

Accidental : happening by chance, unintentionally, or unexpectedly.

Casual : happening by chance; accidental.

Synonym of Casual is Accidental