Of the following hazardous material classes, which is the most dangerous?
1) Class 1: Explosives
2) Class 2: Gases
3) Class 3: Flammable Liquids
4) Class 4: Flammable Solids
5) Class 5: Oxidizing Substances
6) Class 6: Toxic and Infectious Substances
7) Class 7: Radioactive Materials
8) Class 8: Corrosive Substances
9) Class 9: Miscellaneous Dangerous Substances