Option B (One-third) is correct. According to the textbook, areas receiving less than 75 cm of annual rainfall include: (1) Areas of Low Rainfall (50-100 cm) - Western Uttar Pradesh, Delhi, Haryana, Punjab, Jammu and Kashmir, eastern Rajasthan, Gujarat and Deccan Plateau; and (2) Areas of Inadequate Rainfall (below 50 cm) - Parts of Peninsula (Andhra Pradesh, Karnataka, Maharashtra), Ladakh and most of western Rajasthan. Together, these regions constitute approximately one-third of India's total geographical area.