The correct answer is A) 10 nautical miles from the coast.
The primary marine fishing zone in Karnataka lies within 10 nautical miles from the coast. This zone is known as the Exclusive Economic Zone (EEZ) and it is a maritime zone over which a country has special rights over the exploration and exploitation of marine resources. The EEZ of India extends up to 200 nautical miles from the coast. However, the primary marine fishing zone in Karnataka is limited to 10 nautical miles from the coast. This is because the state has a long coastline and a large population of fishermen who depend on marine fishing for their livelihood. By limiting the primary marine fishing zone to 10 nautical miles, the government of Karnataka is trying to ensure that the resources in this zone are not depleted and that the fishermen are able to earn a livelihood.
Option B is incorrect because the primary marine fishing zone in Karnataka lies within 10 nautical miles from the coast, not 20 nautical miles.
Option C is incorrect because the primary marine fishing zone in Karnataka lies within 10 nautical miles from the coast, not 50 nautical miles.
Option D is incorrect because the primary marine fishing zone in Karnataka lies within 10 nautical miles from the coast, not 100 nautical miles.