What is the use of long roots in thorny plants?

Correct answer: Finding moisture deep below

The direct answer is option C, finding moisture deep below. Thorny plants usually grow in dry or semi-arid regions where surface water is limited. To survive, they develop long roots that can travel deep into the soil and reach underground moisture. Many also have small leaves or spines, which reduce water loss, but this question specifically asks about the use of long roots. Option C is correct because deep roots help the plant obtain water below the dry surface. Option A, holding snow, is not the purpose of roots and thorn plants are not generally snow-adapted vegetation. Option B, floating in sea water, is a function related to aquatic plants or buoyant structures, not roots of desert plants. Option D, stopping tides, concerns coastal barriers or mangroves, not the underground root system of thorny plants. The reasoning cue is: dry climate means scarce surface water, so long roots search deeper for moisture. Do not confuse long roots with thorns; roots obtain water, while thorns help reduce grazing and may reduce water loss by replacing leaves.