<p>In this problem the correct answer is D., but I don't understand why C is incorrect.</p>
<ol>
<li>Jacob Lawrence is best known for his depictions of modern urban life, and his celebrated painting Forward presents a rural scene from the life of abolitionist Harriet Tubman</li>
</ol>
<p>(C) Jacob Lawrence is best known for his depictions of modern urban life, however</p>
<p>(D) Although Jacob Lawrence is best known for his depictions of modern urban life,</p>
<p>C wouldn’t be incorrect, it’s just that D has a subordinate conjunction that makes the first clause dependent, which is how it should be. Without the “although” appearing in the beginning, it would sound like an independent clause and for sentences that require you know your conjunctions, its just more convenient to go with answers like D. There’s no rule to describe why D is correct; simply, it just is better.</p>
<p>C is wrong,
however can be used only when there is a semicolon before it and a colon after it,thus C wouldn’t be right.
At the same time D is right and it presents a contrast meaning.</p>