I believe because it falls across multiple lines without obvious breaks. The line breaks are important because the first word of each line gets emphasis.
D. Shells
You can ignore all of the words after of until the verb (of marine mollusks)
So it's just shells are taken...
The correct answer is: [A]:
___________________________________________________________
"brief in-text citations connected to a works cited page" .
___________________________________________________________
"Use complete sentences to start getting your main points together for your actual composition<span>. </span>Write<span> a thesis statement. Your thesis statement will guide your entire </span>composition<span>, and is maybe the single most important part of </span>writing<span> a good </span>composition<span>."</span>