Not 100% sure, but I think its D.
Answer:
The Dred Scott case, also known as Dred Scott v. Sanford, was a decade-long fight for freedom by a black slave named Dred Scott. The case persisted through several courts and ultimately reached the U.S. Supreme Court, whose decision incensed abolitionists, gave momentum to the anti-slavery movement and served as a stepping stone to the Civil War.
In tracking the US economy and determining consumer spending levels an item that might be included would be Harry Potter books sold in bookstores. The other examples are costs incurred by businesses in producing goods or services, whereas the books are solely a consumer purchase.
Because it offers the historian an objective snapshot of the public sentiment of the time, which the cartoonist (should be) distilling for their readers, according to their feelings, for mass appeal. I say objective as it is usually very easy to decipher their subjective viewpoint according to the publication. The value of this is that it is tapping into how the masses 'feel' rather than how subjective facts can be built to form historical opinion. It becomes especially valuable prior to this century, when public sentiment is harder to garner as we were less technologically advanced.
