Assertion (A): Most of the hot deserts are present on the western margin of the continents close to the zones of trade winds. Reason (R): Zones of trade winds are characterized by seas having reversal of planetary wind direction.

Answer: (c) A is true but R is false

A is true (Sahara, Atacama, Kalahari); R wrongly describes trade-wind zones.

The idea

Trade winds are part of the regular flow from subtropical high pressure towards the equatorial low. Rotation gives them an easterly component in both hemispheres. Their belt shifts during the year, but this is different from a monsoon’s seasonal wind reversal. Distinguish movement of a wind belt from reversal of its prevailing direction.

Air descends near subtropical highs → Surface air moves towards equatorial low pressure → Rotation bends the flow → North-east and south-east trades develop → Dry descending and offshore conditions favour many subtropical western deserts

Why the others are wrong

(a) R is false.

(b) R is false — trade winds are steady, not reversing.

(d) A is true.

The trap

Wind reversal belongs to monsoon regions.

Elimination technique

The reason describes seasonal reversal, which belongs to monsoon circulation rather than steady trades. Reject R; the broad desert-location assertion remains true in the textbook context, giving (c).

Also know

Monsoon circulation involves a marked seasonal change in prevailing winds. Westerlies lie poleward of the subtropical highs; polar easterlies lie farther poleward. Sahara, Namib and Atacama illustrate subtropical aridity through different combinations of sinking air, currents and local relief. Not all deserts lie on western coasts.