Final answer:
The elementary substances in the given options are iodine (I) and neon (Ne).
Step-by-step explanation:
The elementary substances in the given options are iodine (I) and neon (Ne). Cyclooctasulfur (S8) is not considered an elementary substance because it consists of multiple sulfur atoms bonded together. Radon (Rn) is a noble gas, but it is not considered an elementary substance because it is made up of multiple radon atoms bonded together.
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