<p>I posted this within another thread but no one seemed to answer my question. </p>
<p>Sam LIKED to read NOVELS, of WHICH he found mysteries ESPECIALLY gripping. NO ERROR</p>
<p>The answer is WHICH while I first put No Error.</p>
<p>Doing some research on relative pronouns, is it because the phrase "of which" isn't acting like a true relative clause</p>
<p>Its SAT grammar, the SAT writers have different grammar rules, then the ones were taught in High School. I would review this: <a href=“http://www.thecriticalreader.com/general-grammar-tips/sat-grammar/item/264-complete-sat-grammar-rules.html”>http://www.thecriticalreader.com/general-grammar-tips/sat-grammar/item/264-complete-sat-grammar-rules.html</a> :)</p>