The first one is D and the second one is C. If your having trouble with grammar just remember that if you take the sentence out of context, like out of the sentence, like what i just did there<-- the sentence should make scence without the comma sentence in it. An example would be Bob, my art teacher, plays the guitar. If you take my art teacher out of context and read it it says bob plays the guitar. Im sure your really good at grammar it just takes time:) i believe in you:)
For the first one is the variant D because ' <span> the largest U.S. state ' it's a developed apposition which mostly are isolated through commas.
For the second one the correct answer it's variant C because '</span><span>a pack of baseball cards' it's also a developed apposition and because the sentence ends in that way we use a dot instead of comma.</span>
