To get the correct answer for the Brain Tree's Quest, you must get the quest, then get a quest from the Esophagor. The Esophagor will first give you the date of death, then the place of death after finishing the second quest for him. The answer changes each time, because the characters are fictional: they exist only in the Brain Tree's mind, which is why you can't guess the correct answer. Even if you guess correctly, it will be wrong if you have not done the quests for the Esophagor. BE WARNED, the reward from the Brain Tree will almost always be worth less than what you paid to feed the Esophagor, and Brain Tree Quest scores are not cumulative like Jhudora's or Illusen's, so your best chance of winning a trophy will be on the first day of every month.