There is some concern regarding the nanoparticles of some chemical elements that are used by the industry in the manufacture of various products. Why? (1). They can accumulate in the environment, and contaminate water and soil. (2). They can enter the food chains. (3). They can trigger the production of free radicals. Select the correct answer using the code given below.

Answer D is correct; all three statements hold. The concept is the environmental behaviour of engineered nanoparticles such as nano-silver, nano-zinc oxide and nano-titanium dioxide, widely used in cosmetics, paints, textiles and packaging.

• Statement 1 is correct. Nanoparticles are very small and highly reactive, so they persist, settle in sediments and soil, and build up over time, contaminating water bodies and land.
• Statement 2 is correct. Plants take up nanoparticles from soil and water, and they then move up through herbivores and predators. Aquatic organisms at the base of the food web ingest them, so biomagnification concerns follow.
• Statement 3 is correct. Many nanoparticles, notably metal oxides and carbon-based forms, generate reactive oxygen species. This oxidative stress damages cell membranes, proteins and DNA.

Mains link: Environment (emerging pollutants) and Science and Technology (nanotechnology regulation). Regulation in India remains thin, a fair GS-3 angle.

Trap: Candidates assume commercial use implies only benefits and drop statement 2 without reasoning. Small size, persistence and reactivity make all three true.