Natives planted the fruit across South and Central America and in the Caribbean region, 23 Christopher Columbus first found it.
答案：(D) where
關係副詞 where 引導地方子句，「在……那裡哥倫布首次發現了它」；that／what／which 都不能這樣引導子句來表達「在某地」的地點語意。
where 你最熟的身分是疑問詞「在哪裡」，所以看到它出現在逗號後面會覺得陌生。這裡的 where 是關係副詞，前面那一整片加勒比海地區就是它的先行詞，整個子句在補充說明「哥倫布就是在那裡第一次見到鳳梨的」。
用最可靠的一招：數一數空格後面的子句缺不缺成分。Christopher Columbus first found it 的主詞、動詞、受詞都齊了，一個名詞位置都不缺；而 that、which、what 都是關係代名詞，進到子句裡一定要當主詞或受詞，這裡沒有空位給它們，所以只能填不占名詞位置的關係副詞 where。還原成兩句話驗算：Natives planted the fruit in the Caribbean region. ＋ Columbus first found it there.——there 就是 where 的來源。where 也可以寫成 in which，兩種說法指的是同一件事。這一格鑑別度 60，分開的正是「有沒有動手數子句成分」這個習慣。
that 還多一個問題：它不能用在逗號後面的補充說明子句（劍橋 English Grammar Today 的關係子句條目）。which 若要用，必須補上介系詞成為 in which。what 自己帶著先行詞（＝ the thing that），不能再回頭修飾前面的名詞。101 年第 22 題也考 where，但那一題空格前沒有先行詞，著力點與本題正好相反，兩題可以對著看。
the place where（……的那個地方）、the reason why（……的原因）、the day when（……的那一天）、in which（＝ where，在其中）、the Caribbean region（加勒比海地區）、plant a crop（種植作物）
The pineapple, long a symbol of Hawaii, was not a native plant. 21 , pineapples did not appear there until 1813. The pineapple was 22 found in Paraguay and in the southern part of Brazil. Natives planted the fruit across South and Central America and in the Caribbean region, 23 Christopher Columbus first found it.
Columbus brought it, along with many other new things, back to Europe with him. From there, the tasty fruit 24 throughout other parts of civilization. It was carried on sailing ships around the world because it was found to help prevent scurvy, a disease that often 25 sailors on long voyages. It was at the end of one of these long voyages that the pineapple came to Hawaii to stay.