In 1983, Eli lilly, an American company prepared two DNA sequences corresponding to A and B chains of human insulin and introduced them in plasmids of ..A.. to produce insulin chains. Chains A and B were produced separately extracted and combined by creating ...B... to from human insulin.
Choose the option which correctly fills the blank marked as A and B in the given paragraph

Options

A. `{:(a,b),("E. coli","Hydrogen bond"):}`
B. `{:(a,b),("E. coli","Phospodiester bond"):}`
C. `{:(a,b),("Ti plasmid","Disulphide bonds"):}`
D. `{:(a,b),("E. coli","Disulphide bonds"):}`

Answer

To solve the question, we need to identify the correct terms to fill in the blanks marked as A and B in the provided paragraph about the production of human insulin by Eli Lilly in 1983.

### Step-by-Step Solution:

1. **Understanding the Context**:
- The question refers to the process of producing human insulin using recombinant DNA technology.
- Two DNA sequences corresponding to the A and B chains of insulin were prepared.

2. **Identifying Blank A**:
- The blank A is where we need to identify the organism or system used to introduce the DNA sequences for the production of insulin chains.
- The options provided include various terms, but we know that the most common organism used in genetic engineering for producing proteins is *E. coli* (Escherichia coli).
- Therefore, the correct term for blank A is **E. coli**.

3. **Identifying Blank B**:
- The blank B refers to the type of bond formed when the A and B chains of insulin are combined.
- The A and B chains of insulin are connected by a specific type of bond. In the case of insulin, the chains are linked by **disulfide bonds**.
- Thus, the correct term for blank B is **disulfide bond**.

4. **Final Answer**:
- The correct options to fill in the blanks are:
- A: **E. coli**
- B: **disulfide bond**

### Conclusion:
The final answer is:
- A: E. coli
- B: disulfide bond