Plants that grow and exist in deserts have highly specialized means of adapting themselves to the arid environment.

Answer: Option D

Unproductive : not producing or able to produce large amounts of goods, crops, or other commodities.
Useless : not fulfilling or not expected to achieve the intended purpose or desired outcome.
Withering : intended to make someone feel humiliated; scornful.
Dry : free from moisture or liquid; not wet or moist.
Arid : (of land or a climate) having little or no rain; too dry or barren to support vegetation.

Synonym of Arid is Dry