考托詞彙第338題 - 英檢

之前版上有人分享一份考托詞彙
第338題的答案讓我質疑了
原題如下

Overland transport in the United States was still extremely
PRIMITIVE in 1790. Roads were few and short, usually extending from island
communities to the nearest river town or seaport.
(A) unsafe
(B) unknown
(C) inexpensive
(D) undeveloped

問的是primitive這個單字的同義詞
答案是C,可是我覺得應該是D
不知道有人可以幫忙解釋一下的嗎?
謝謝

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