Mycorrhizal biotechnology has been used in rehabilitating degraded sites because mycorrhiza enables the plants to 1. resist drought and increase absorptive area 2. tolerate extremes of pH 3. resist disease infestation Select the correct answer using the codes given below.

Mycorrhiza is a symbiotic association between fungal hyphae and plant roots. The fungus extends the effective absorptive surface far beyond what root hairs can cover, mainly for phosphorus and water. That is why statement 1 is correct: the plant gains drought resistance and a larger absorptive area.

Statement 2 is also correct. Mycorrhizal hyphae help plants survive in acidic, alkaline or metal-contaminated soils, which is why they are useful in reclaiming mine spoils and other degraded land. Statement 3 holds too: the fungal sheath and hyphal network act as a physical barrier, and some mycorrhizae produce antibiotic-like compounds that improve resistance to root pathogens.

So all three statements hold, and the answer is D. Options A, B and C each drop at least one valid statement.

Core concept: symbiosis and ecological restoration. For Mains GS-3 (environment and biodiversity), this links to soil reclamation, bioremediation and afforestation of wastelands, where mycorrhizal inoculants help establish vegetation.

Trap: candidates often doubt statement 2 because pH tolerance sounds like a specialised trait. The question asks about the general benefit of the association, and that benefit is well documented.