**Core Concept**
Mummification is a natural process where the soft tissues of a deceased organism are preserved due to environmental conditions that prevent decay and putrefaction. This process is influenced by factors such as low humidity, arid climate, and lack of oxygen.

**Why the Correct Answer is Right**
Mummification occurs when the deceased individual is exposed to a dry environment, such as a desert or a dry cave. The low humidity and arid climate prevent the growth of bacteria and fungi, which are responsible for decomposition. Additionally, the lack of oxygen inhibits the breakdown of tissues by microorganisms. In such conditions, the skin and other tissues can dry out and shrink, resulting in the formation of a mummy.

**Why Each Wrong Option is Incorrect**
**Option A:** High humidity and warm temperatures are conducive to rapid decomposition and decay.
**Option B:** High altitudes with low oxygen levels are not typically associated with mummification, as the lack of oxygen can actually promote decomposition.
**Option C:** Areas with high rainfall and flooding are unlikely to produce mummies, as the presence of water facilitates the growth of microorganisms that break down tissues.

**Clinical Pearl / High-Yield Fact**
Mummification is often seen in arid regions, such as the deserts of Egypt and the Andes mountains, where the dry conditions preserve the bodies of deceased individuals.

**Correct Answer: D.**