BB pg 601 3rd edition writing questions?

Test Preparation SAT Preparation
1

<h1>16</h1>

<p>Along(a) the curve of islands known as the Florida Keyes lies(b) a reef of living coral, the only one(c) of a kind(d) in the continental United States. </p>

<p>Why is D gramatically incorrect?</p>

<p>And who thinks the critical reading is easier in this book? or is it just me? ;)</p>

2

<p>I believe it should be “of its kind”. I think it’s an idiomatic error.</p>