New Mangalore Port is the major sea port located in Karnataka. It caters to the export of iron ore concentrates from Kudremukh mines.
Source: Major Sea Ports, Chapter 7
For map-based 1-mark questions, examiners expect the exact name of the port. "New Mangalore" (not just "Mangalore") is the correct and complete name as given in the textbook. Mentioning its significance (Kudremukh iron ore export) adds value and confirms you haven't confused it with Mormugao (Goa).