High energy phosphates required to form one peptide bond:

**Core Concept**
During protein synthesis, the formation of a peptide bond between amino acids requires energy input. This energy is utilized to drive the condensation reaction, where the carboxyl group of one amino acid reacts with the amino group of another, releasing water and forming a peptide bond. The process is facilitated by the enzyme ribosome and the energy-rich molecule ATP.

**Why the Correct Answer is Right**
The correct answer is ATP, which provides the necessary energy for the peptide bond formation. When ATP is hydrolyzed to ADP and inorganic phosphate, the energy released is used to drive the condensation reaction, allowing the peptide bond to form between the amino acids. This process is crucial for the elongation of the polypeptide chain during protein synthesis. The energy from ATP is transferred to the ribosome, where it is used to drive the peptide bond formation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because GTP is not directly involved in the formation of peptide bonds during protein synthesis. GTP is involved in other stages of protein synthesis, such as initiation and elongation, but not in the actual formation of peptide bonds.

**Option B:** This option is incorrect because NADH is not directly involved in the formation of peptide bonds during protein synthesis. NADH is a coenzyme involved in various redox reactions, but it is not the primary energy source for peptide bond formation.

**Option C:** This option is incorrect because Pi (inorganic phosphate) is not the primary energy source for peptide bond formation. While Pi is released during the hydrolysis of ATP, it is not the direct energy source for the formation of peptide bonds.

**Clinical Pearl / High-Yield Fact**
The energy required for peptide bond formation is a critical aspect of protein synthesis, and any disruption to this process can lead to errors in protein synthesis, resulting in premature termination or misfolded proteins.

**Correct Answer: C. 25.8 kJ/mol**