This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nuclear medicine, Subject name: Radiology
Parent compound of Tc-99m is 
Select and explain. 
A. Strontium -99, B. Molybdenum-99, C. Rubidium-99, D. Cs-137
B: Molybdenum-99
Answer: B: Molybdenum-99 
Explanation: None