Which option wrongly mixes area and length in understanding India's size?

Correct answer: (3.28) million sq km is coastline length

The direct answer is D. The mistake in option D is that it calls 3.28 million square kilometres the length of India’s coastline. A square kilometre is a unit of area, not a unit of length. India’s area is approximately 3.28 million square kilometres, whereas coastline and boundary figures are expressed in kilometres. Option A is correct because 3.28 million sq km describes India’s area. Option B is correct because 7516.6 km is the commonly cited total coastline including the island groups. Option C is accepted in school geography as the approximate length of India’s land boundary, about 15,200 km. Option D is wrong because it mixes the correct area number with the wrong meaning and the wrong type of measurement: an area cannot be called coastline length. The key reasoning is to check both the number and its unit: ‘square km’ means surface area; ‘km’ means distance or length. Memory cue: area has square units, while borders and coastlines have ordinary kilometres.