16. ______ of coffee, do you know that civet cat coffee is the most expensive in the world?
(A) Referring
(B) Speaking
(C) Regarding
(D) Thanks

提到，談及，談起

speaking of sb / sth= talking of sb / sth =refer to sb/sth  

regarding = in /with regard to = about    + N.

【regard用法】
regard (v.) 將~認為、看待
I always regard her as a role model.
(我一直把她當作榜樣。)
Her parents always regarded her as the smartest of their children.
(她父母一貫把她看作是所有子女中最聰明的。)

regard (n.) 尊敬、關注
I have a high regard for her intelligence and hard work.
(我很欣賞她的智慧和勤奮。)
He has no regard for other people's feelings.
(他毫不尊重別人的感情。)

regards (n.) 問候、致意
Please send my regards to your mother if you see her.
(如果見到你母親，請代我問候她。)

in this/that regard (ph.) 在這/那方面上
In this/that regard, I completely agree with your assessment of the situation.
(在這/那方面，我完全同意你對情況的評估。)

in/with regard to=as regards=regarding 關於、至於(=about)
In regard to the matter we discussed, I have made a decision.
=With regard to the matter we discussed, I have made a decision.
=As regards the matter we discussed, I have made a decision.
=Regarding the matter we discussed, I have made a decision.
(關於我們討論的事情，我已經做出了決定)

參考資料：
https://english.cool/regarding/
https://barshai.org/word-dive/regard/
Cambridge Dict.