Answer:
!!!ALWAYS START WITH A DRAFT WHEN MAKING LETTERS!!!
(Formal letter because a teacher is your superior and elder)
Dear Mr./Mrs.(insert name),
(This paragraph must state why this letter is being sent and the main point/s of this letter)
(This Paragraph must explain the importance of your point providing evidence of course. You can use statistics to strengthen your points, such as quantifiable metrics, facts, and etc.)
(This paragraph should provide background information to back up your reasons.)
(End the letter by reiterating your points, and if you can, put in a call to action.)
Respectfully/Sincerely,
[name of recipient]
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>