To answer this question, we need to understand the context of Voldemort's wand. In the Harry Potter series, Voldemort's wand is known as the "Elder Wand" or the "Deathstick."
The correct answer is C) phoenix.
The feather used in Voldemort's wand is from a phoenix. In the series, it is revealed that the core of Voldemort's wand contains a tail feather from Fawkes, Albus Dumbledore's phoenix. The feather was taken from Fawkes and used as the core for Voldemort's wand during the wand-making process.
Therefore, option C) phoenix is the correct answer.