Assertion:. Highways in Russia are not as important as railways.
Reasoning: In Russia, railways account for about 90 per cent of the country

Both Assertion (A) and reasoning (R) are correct and but R is not the correct explanation of A.

The correct answer is Option 2: Both Assertion (A) and reasoning (R) are correct and but R is not the correct explanation of A.

Assertion:. Highways in Russia are not as important as railways. This is correct. because highways are less important in Russia due to its vast geographical extent and extreme climatic conditions. Construction and maintenance of roads are difficult in many regions, especially areas affected by snow and permafrost.
Reasoning: In Russia, railways account for about 90 per cent of the country. This is correct.

Does R explains A?

No. The reason tells us that railways are widely used, but it does not explain why highways are less important. The actual explanation is the harsh climate and large territorial extent of Russia.

NCERT: "In Russia, a dense highway network is developed in the industrialised region west of the Urals with Moscow as the hub. The important Moscow-Vladivostok Highway serves the region to the east. Due to the vast geographical area, highways in Russia are not as important as railways. In Russia, railways account for about 90 per cent of the country’s total transport with a very dense network west of the Urals."