In the sentence B <em>'Samuel noted that the flowers "... in boxes grew larger</em> <em>than those planted in pots.'</em> the use of the ellipsis is incorrect because the sentence is stating something that Samuel noted but, by placing the ellipsis right before the words <em>in boxes, </em>it prevents the function they have, which is of modifying the noun<em> flowers, </em>also the verb is missing.
Fifty cents is a plural noun since it is talking about more than one cent. In the example, you would say, "fifty cents <em>is </em>how much I owe you".
