Final answer:
The maximum allowable limit of morphine for a substance to be classified as Schedule III is 50 milligrams per 100 milliliters or per 100 grams.
Step-by-step explanation:
The question pertains to the classification of morphine under the Controlled Substances Act's scheduling system. Specifically, the student is inquiring about the maximum allowable limit of morphine for a substance to be classified as a Schedule III drug. The correct maximum allowable limit for morphine to be classified as Schedule III is 50 milligrams per 100 milliliters or per 100 grams of compound, according to the United States Drug Enforcement Administration's (DEA) regulations.