Option (C) Assam is the correct answer. According to the textbook context, 'Assam, West Bengal and Bihar are among the high flood-prone states of India.' The text specifically mentions 'Frequent inundation of agricultural land and human settlement, particularly in Assam, West Bengal, Bihar and Eastern Uttar Pradesh.' While Bihar, West Bengal, and Assam are all classified as 'high flood-prone' states, Uttar Pradesh is described as being 'vulnerable to occasional floods' - not frequent. Additionally, the textbook includes 'Figure 6.5: Brahmaputra During Flood,' highlighting Assam's association with frequent flooding. Among the given options, Assam experiences the most frequent and severe floods due to the Brahmaputra river.