The complementary, synthetic and random DNA are used as :

Options

A. Cloning vectors
B. Recombinant DNA
C. Transposons
D. Passenger DNA

Answer

To solve the question regarding the use of complementary, synthetic, and random DNA, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Types of DNA**:
- **Complementary DNA (cDNA)**: This is synthesized from a messenger RNA (mRNA) template through the process of reverse transcription. It is often used in cloning and gene expression studies.
- **Synthetic DNA**: This refers to artificially created DNA sequences that can be designed to have specific properties or functions. It is often used in various biotechnological applications.
- **Random DNA**: This typically refers to DNA sequences that are generated without a specific template or design, often used in genomic studies or for creating libraries of genetic material.

2. **Identifying the Purpose of Each Type**:
- **Passenger DNA**: This is the DNA that is transferred from one organism to another. It can include complementary, synthetic, or random DNA that is inserted into a host organism for various purposes, such as gene therapy or genetic modification.
- **Cloning Vectors**: These are DNA molecules used to carry foreign DNA into a host cell for replication and expression. They do not specifically refer to complementary, synthetic, or random DNA.
- **Recombinant DNA**: This is DNA that has been formed artificially by combining constituents from different organisms. It is a broader category that may include passenger DNA but is not limited to it.
- **Transposons**: Also known as "jumping genes," these are sequences of DNA that can change their position within the genome. They are not directly related to the complementary, synthetic, or random DNA types mentioned.

3. **Conclusion**:
- Based on the definitions and purposes of the different types of DNA, the complementary, synthetic, and random DNA are primarily used as **passenger DNA**. This is because they can be transferred into host organisms to achieve specific genetic modifications or functions.

### Final Answer:
The complementary, synthetic, and random DNA are used as **passenger DNA**.

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