The correct answer is A. ordinary.
The word “casual” means “not done or happening in a serious or careful way.” The word “ordinary” means “normal or usual.” The word “incidental” means “happening by chance or as a secondary result of something else.” The word “funny” means “causing laughter or amusement.” The word “accidental” means “happening by chance.”
In the sentence “There was nothing casual about my father’s interests,” the word “casual” is used in the sense of “not done or happening in a serious or careful way.” The
sentence means that my father’s interests were not ordinary or usual. They were something that he was passionate about and that he took seriously.The other options are not correct because they do not convey the meaning of the sentence. The word “incidental” is not correct because it means “happening by chance or as a secondary result of something else.” The word “funny” is not correct because it means “causing laughter or amusement.” The word “accidental” is not correct because it means “happening by chance.”