Given below are two statements, one labelled as Assertion and the other labelled as Reason (R) Assertion (A): Mangroves are very specialized forest eco-systems of tropical and sub-tropical regions bordering certain seacoasts. Reason (R): They stabilize the shoreline and act as bulwark against encroachments by the sea. In the context of the above two statements, which one of the following is correct?

Answer: (b) Both A and R are true but R is not a correct explanation of A

Both are true; R is a benefit, not the cause.

The idea

Mangroves are trees and shrubs adapted to saline or brackish tidal settings. Their salt-handling and root adaptations explain why they survive there. Protecting a shoreline is a result of that vegetation, so a useful function is not automatically the cause of a specialised ecosystem.

Sheltered tidal coast → Saline water and waterlogged soil → Salt-tolerant plants establish → Specialised roots tolerate poor soil aeration → Roots and stems slow water → Sediment is trapped and shore erosion is reduced

Why the others are wrong

(a) R describes what mangroves do; it does not explain why they exist where they do.

(c) Mangroves do protect shorelines.

(d) Mangroves are specialised coastal ecosystems.

The trap

In A–R questions, a benefit is almost never the cause.

Elimination technique

Test the explanatory link separately from truth: “they protect the shore” describes a benefit, without explaining salt tolerance or tidal adaptation. Both statements can be true while the reason does not explain the assertion.

Also know

Avicennia has breathing roots called pneumatophores; Rhizophora commonly has stilt roots. Several mangroves show vivipary, with seedlings developing while attached to the parent. Sundarbans is a deltaic mangrove system, while coral reefs need different conditions, including clearer water.