An explant is

Options

A. bud of a plant .
B. virus infected part of plant.
C. the part of the plant used in tissue culture.
D. the part of the plant that expresses a specific gene.

Answer

**Step-by-Step Solution:**

1. **Understanding the Term "Explant":**
- The term "explant" originates from the concept of explant culture, which is a type of tissue culture. It refers to a piece of tissue taken from a plant or animal for the purpose of growing or studying cells in vitro (outside of their natural environment).

2. **Identifying the Source of the Explant:**
- An explant can be derived from various parts of a plant, including leaves, stems, roots, or buds. It is important to note that the explant is a specific portion of the plant tissue that will be used for further cultivation or experimentation.

3. **Isolating Cells from the Tissue:**
- Once the explant is obtained, the next step involves isolating cells from this tissue. This process is crucial for tissue culture as it allows researchers to work with specific cells for studies or propagation.

4. **Defining the Correct Answer:**
- Among the options provided, the correct definition of an explant is "Part of a plant used in tissue culture." This option accurately describes what an explant is and its role in tissue culture.

5. **Eliminating Incorrect Options:**
- The other options, such as "bud of a plant," "virus infected part of a plant," and "part of a plant that expresses a specific gene," do not accurately define an explant. An explant is not limited to buds or specific gene expression, nor is it necessarily virus-infected.

**Final Answer:**
- An explant is defined as a part of a plant used in tissue culture.

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