With reference to Indian transport systems, consider the following statements: 1. Indian railways system is the largest in the world. 2. National Highways cater to 45 per cent of the total road transport demand. 3. Among the states, Kerala has the highest density of surface road. 4. National Highway No. 7 is the longest in the country. Which of these statements are correct?

1. Statement 1 is incorrect. While the Indian Railways system is one of the largest in the world (typically ranked 4th or 5th by network length), it is not the largest overall (countries like USA, China, Russia have larger networks). 2. Statement 2 is approximately correct. National Highways (NH) constitute a small percentage of India's total road network length, but they carry a disproportionately large share of the total road transport traffic (freight and passenger). Estimates around 2001-2002 often placed this share around 40-45 per cent. 3. Statement 3 is incorrect. While Kerala has a high population density and a relatively dense road network, other states like West Bengal or Punjab often had higher density of surface road (measured as road length per unit area or per unit population) around that period. 4. Statement 4 is correct. At that time (before significant additions and renumbering), National Highway No. 7 (NH 7), connecting Varanasi to Kanyakumari, was considered the longest single National Highway in the country. 5. Therefore, statements 2 and 4 are correct.