The correct answer is
D: The Jewish population of America at the turn of the century was overwhelmingly Ashkenazic, and one of their dietary rules at Passover time was the prohibition against eating kitniyot, or legumes. Included in this category were beans, and it was wrongly believed that coffee beans were (as the name says) beans! In fact they are actually fruit, and are not included in the kitniyot restriction, but most Jews simply did not know this. The promotion of Maxwell House coffee as actually being kosher for Passover began in 1923 with ads run in the Forverts newspaper noting the kosher certification by an obscure Lower East Side rabbi. A few years later they made the decision to publish a haggadah as a giveaway with Maxwell House coffee purchases to further promote their product.