Final answer:
Runespoor divination is the often overlooked type of divination class offered at Ilvermorny since 1926, where many methods exist but Runespoor is specifically magical in nature. The correct option is d.
Step-by-step explanation:
The often overlooked type of divination that has been offered as an extracurricular class at Ilvermorny since 1926 is d) Runespoor divination. Divination is the practice intended to gain understanding, guidance, or advice about an event or situation, and it has been part of various cultures around the world.
While there are many methods of divination, including scapulimancy, tasseomancy, oomancy, bibliomancy, tarot card reading, and checking astrological signs, Runespoor divination is particularly unique to the wizarding world, depicting the specialized practice involving Runespoors, a magical three-headed serpent. The correct option is d.