No change in the genotype of the varieties is observed in the following crop improvement methods
(I) Purelie selection (II) Mass selection
(III) Clonal selection (IV) Introduction

Options

A. I and IV
B. ii and iii
C. I and II
D. III and IV

Answer

To answer the question regarding which crop improvement methods show no change in the genotype of the varieties, we can analyze each method mentioned:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for crop improvement methods where there is no change in the genotype of the varieties. This means that the offspring produced through these methods should have the same genetic makeup as the parent plants.

2. **Analyzing Each Method**:
- **(I) Pureline Selection**: This method involves selecting a single homozygous line from a population. Since the selected line is purebred, the genotype remains unchanged. Therefore, this method does not alter the genotype.
- **(II) Mass Selection**: In mass selection, a large number of plants are selected based on desirable traits, but they are not necessarily genetically uniform. However, the selected plants can still produce offspring with similar genotypes. Thus, there is no significant change in genotype.
- **(III) Clonal Selection**: This method involves selecting and propagating plants that have desirable traits. Since clones are genetically identical to the parent plant, there is no change in genotype.
- **(IV) Introduction**: This method involves introducing new varieties or species into an area. This can lead to hybridization and changes in genotype, so it does not fit the criteria of having no change in genotype.

3. **Conclusion**: Based on the analysis:
- The methods where no change in genotype is observed are:
- (I) Pureline Selection
- (II) Mass Selection
- (III) Clonal Selection

### Final Answer:
The crop improvement methods where no change in genotype of the varieties is observed are:
- (I) Pureline Selection
- (II) Mass Selection
- (III) Clonal Selection