This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nucleotides, Subject name: Biochemistry
PRPP (Phospho Ribosyl Pyro Phosphate) is used in : 
Select and explain. 
A. Purine synthesis & Pyrimidine synthesis, B. Histidine synthesis, C. Niacin synthesis, D. All
D: All
Answer: D: All 
Explanation: Phosphoribosyl Pyrophosphate(PRPP) is used in the synthesis of : 1. Purine 2. Pyrimidine 3. Histidine 4. Niacin synthesis from Tryptophan. NOTE: Phosphoribosyl pyrophosphate (PRPP) paicipates in pyrimidine biosynthesis only subsequent to assembly of the pyrimidine ring. PRPP serves as a scaffold for assembly of the purine ring in purine biosynthesis. The first intermediate formed in the de novo pathway for purine biosynthesisis 5-phosphoribosyl 1-pyrophosphate (PRPP).