The radioactive pollution may result from: 1. medical waste 2. coal ash 3. production of nuclear arsenal 4. mining of uranium 5. decommissioning of nuclear weapons The correct causes are: (a) 1, 3 and 4 only (b) 1, 3, 4 and 5 only (c) 2, 3, 4 and 5 only (d) 1, 2, 3, 4 and 5