Analyze the statement given below regarding the thermal cycler and select the option that shows incorrect statements.
I. Annealing is also called the hybridization of oligonucleotide (primer).
II. During extension, DNA polymerase polymerizes nucleotides in `5'rarr 3'` direction.
III. Denaturation is a process of formation of H- bonds.

Options

A. I and III
B. Only II
C. Only III
D. I and II

Answer

To analyze the statements regarding the thermal cycler and identify the incorrect one, we will evaluate each statement step by step.

### Step-by-Step Solution:

1. **Statement I: Annealing is also called the hybridization of oligonucleotide (primer).**
- **Analysis:** In the context of PCR (Polymerase Chain Reaction), annealing refers to the binding of primers (short sequences of nucleotides) to the complementary sequences on the single-stranded DNA template. This process is indeed referred to as hybridization. Therefore, this statement is **correct**.

2. **Statement II: During extension, DNA polymerase polymerizes nucleotides in the 5' to 3' direction.**
- **Analysis:** During the extension phase of PCR, DNA polymerase synthesizes a new DNA strand by adding nucleotides to the growing strand in the 5' to 3' direction. This is a fundamental principle of DNA synthesis. Hence, this statement is also **correct**.

3. **Statement III: Denaturation is a process of formation of H-bonds.**
- **Analysis:** Denaturation refers to the process of breaking the hydrogen bonds between the two strands of DNA, resulting in the separation of the double helix into single strands. Therefore, this statement is **incorrect** because denaturation does not involve the formation of hydrogen bonds; rather, it involves their breaking.

### Conclusion:
The incorrect statement is **Statement III**: "Denaturation is a process of formation of H-bonds."