<p>K, so this is the question. It's from the 2008-09 official practice test.</p>
<p>A poetic form congenial to Robert Browning was the dramatic <em>monologue, it let him explore</em> a character's mind without the simplifications demanded by stage productions.</p>
<p>B) monologue, which let him explore
C) monologue that lets him explore</p>
<p>So that's what I had left after some process of elimination. Can someone explain to me why the answer is B and what's the difference in the usage of "which" and "that"?</p>
<p>The original sentence uses the past tense (<em>was</em>), so ‘lets’, which is present tense, is a change of tense and is therefore incorrect. Therefore, the correct answer is B.</p>
<p>In regards to your “which vs that” question, here’s what an article says:
<p>In simple, Use which after a comma and that without a comma; this rule can be applicable on the SAT since that is that is what they test you on basically.</p>
<p>I can’t imagine they would test it. The link Joshtch provided is in conflict with some other grammar sources I’ve referenced; there is not concensus on the usage.</p>
<p>In accordance with the most liberal guideline, “which” can always replace “that.” (The reverse is not, however, necessarily true. “That” cannot act as a relative pronoun for nonessential adjective clauses.)</p>