The nominal cover requirements for meeting the durability requirements of mild, very severe, severe, moderate, extreme types of exposure are respectively in mm
1. 20, 30, 45, 50, 75
2. 20, 45, 30, 50, 75
3. 20, 50, 45, 30, 75
4. 20, 75, 50, 30, 45
5. 20, 50, 60, 75, 90