I believe the answer is
B. This pamphlet calmly disputed the claims that had been made in favor of slavery and provided ordinary citizens and abolitionists with arguments explaining why slavery was wrong.
<span>A) Here is what my mother said to me, at least once: "Jerry, you've got to try a little harder."
Since the quotation from his mother is set off from the rest of the sentence, not continuing it, a colon is appropriate. Additionally, the comma before "at least once" is correct and after "Jerry" is also correct. </span>
