6535. Plants that grow and exist in deserts have highly specialized means of adapting themselves to the arid environment.

✅ The correct answer is 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