I. Treatment of cancerII. Detection of leakages in water mainsIII. Detection of the ages of ancient toolsIV. Preparation of drugs Which combination of the a...

The question is asking which of the combinations refers to the uses of radioactive isotopes. Radioactive isotopes are used in various fields such as medicine, geology, and chemistry. Among the given options, the combination of "I" and "IV" are not related to the uses of radioactive isotopes. Treatment of cancer involves chemotherapy, radiation therapy, and surgery. Preparation of drugs can involve the use of various techniques such as chromatography, filtration, and extraction. The combination of "II" and "III" is also not related to the uses of radioactive isotopes. Detection of leakages in water mains and detection of the ages of ancient tools are typically done using non-radioactive techniques such as acoustic leak detection and carbon dating, respectively. Therefore, the correct answer is the combination of "I, II, and III", as these fields make use of radioactive isotopes.