Final answer:
The most appropriate method to detect 99Mo in the eluate is gamma spectroscopy.
Step-by-step explanation:
The most appropriate method to detect 99Mo in the eluate is gamma spectroscopy. Gamma spectroscopy involves measuring the energy and intensity of gamma rays emitted from a sample. Since 99Mo emits gamma rays during radioactive decay, gamma spectroscopy can be used to detect and analyze its presence.