Oh man! I got so excited when this question came up on the screen last night. Upon reading I instantly time traveled back to 1995 where I was sitting in a circle surrounded by my cousins staying up until 3AM playing Magic the Gathering. Dork Alert! I know.
But literally was so off guard that I got the question wrong. I said “decks” and the answer was “cards” but I challenge that response because they had deck sleeves to protect the decks as well. But I digress. Just another example of Alex Trebek and the Jeopardy crew bringing the heat every week.