Read the following text and answer the following questions on the basis of the same:
Mutation is sudden, discontinuous variation in genotype of an organism due to a change in its chromosomes and genes. Variation in DNA is a result of mutation. It is of three types : Gene mutation, chromosomal aberrations and gametic mutation. Gametic mutation is a change in chromosome number that brings effect on the phenotype, it is of two type - aneuploidy and euploidy. Mutation can be artificially produced by certain agents called mutagen. There are two major types of mutagens: physical and chemical mutagen.
Substitution of a purine with another purine is known as ...... :

Options

A. Transversion
B. Inversion
C. Transition
D. Translocation

Explanation

To answer the question regarding the substitution of a purine with another purine, let's break down the information provided step by step.

### Step-by-Step Solution:

1. **Understanding Mutation**:
- Mutation is defined as a sudden, discontinuous variation in the genotype of an organism due to changes in its chromosomes and genes. This means that mutations can lead to changes in the DNA sequence of an organism.

2. **Types of Mutation**:
- According to the text, mutations can be categorized into three main types: gene mutation, chromosomal aberrations, and gametic mutation. Each type has its implications on the organism's phenotype.

3. **Focusing on Gene Mutation**:
- Gene mutations can be further divided into two types: frameshift mutations and substitutions. This is important for understanding the specific type of mutation being asked about.

4. **Understanding Substitution**:
- Substitution mutations can be classified into two categories: transitions and transversions. This distinction is crucial for answering the question.

5. **Defining Transition**:
- A transition occurs when a purine base (adenine or guanine) is substituted with another purine base. For example, if adenine is replaced by guanine or vice versa, this is known as a transition.

6. **Conclusion**:
- Therefore, the substitution of a purine with another purine is specifically referred to as a "Transition".

### Final Answer:
The substitution of a purine with another purine is known as **Transition**.

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