Which biome has stems for water storage, extensive root system for absorbing water, and modified leaves (spines) ?

The correct answer is desert biome.

Deserts are regions also called drylands because of the conditions found there (like a moisture deficit). Desert plants have to adapt to those dry and hot climates (sometimes without fresh water for years). Some plants have adapted by growing long roots that tap water from deep underground. Others, such as cacti, have special means of storing and conserving water (modifications of leaves for example).