Read this: After 1857, the colonial government strengthened and expanded its infrastructure via the court system, legal procedures, and statutes. The Indian Penal Code came into being. In education, Thomas Babington Macaulay had made schooling a priority for the Raj in his famous minute of February 1835 and succeeded in implementing the use of English as the medium of instruction. By 1890 some 60,000 Indians had matriculated. The Indian economy grew at about 1% per year from 1880 to 1920, and the population also grew at 1%. However, from 1910s Indian private industry began to grow significantly. India built a modern railway system in the late 19th century which was the fourth largest in the world. The British Raj invested heavily in infrastructure, including canals and irrigation systems in addition to railways, telegraphy, roads and ports. However, historians have been bitterly divided on issues of economic history, with the Nationalist school arguing that India was poorer at the end of British rule than at the beginning and that impoverishment occurred because of the British.

When did India build the forth largest rail system in the world?
What is the answer? (If it cannot be answered, return "unanswerable")
late 19th century