Ice Mummies

You chose answer 4.

Burying in cold, deep, stagnant water that contains natural acids.

You're correct. These are the conditions that have produced nearly 2,000 "bog mummies" in Ireland, England, Norway, Denmark, Germany, Russia, and the island of Crete. Some may have accidentally perished where they were found; others may have been buried there. Some show signs of violent death. The bogs' stagnant, oxygen-free water, plus the acids given off by peat moss (especially tannic acid), create an environment unfriendly to decay-causing bacteria.

You're right, but there's more than one way to make a mummy. Try again.