An antibiotic resistance gene in a vector usually helps in the selection of a. Competent cells b. Transformed cells c. Recombinant cells d. None of the above

Options

A. competent cells
B. transformed cells
C. recombinant cells
D. None of these

Explanation

To answer the question "An antibiotic resistance gene in a vector usually helps in the selection of", we will analyze the options provided and understand the role of the antibiotic resistance gene in the context of genetic engineering.

### Step-by-Step Solution:

1. **Understanding the Role of Antibiotic Resistance Genes**:
- Antibiotic resistance genes are often included in vectors used for cloning or transformation. Their primary function is to allow for the selection of successfully transformed cells.

2. **Ligation of Alien DNA**:
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