Desired improved varieties of economically useful crops are raised by

Options

A. Migration
B. Biofertiliser
C. Hybridisation
D. Natural selection

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks how desired improved varieties of economically useful crops are raised. This implies that we need to identify the method or technique used in agriculture to enhance crop varieties.

2. **Identifying the Method**: One of the primary methods used to develop improved varieties of crops is hybridization. Hybridization involves crossing two or more plants that have different genotypes.

3. **Explaining Hybridization**: In hybridization, the plants selected for crossing are chosen based on their desirable traits. When these plants are crossed, they produce offspring that may inherit a combination of traits from both parent plants.

4. **Genetic Recombination**: The process of hybridization leads to genetic recombination, which can result in new traits that are beneficial for agriculture, such as increased yield, disease resistance, or improved nutritional quality.

5. **Resulting Improved Varieties**: The offspring produced through hybridization can be selected for their desirable characteristics, leading to the development of improved varieties of economically useful crops.

6. **Conclusion**: Therefore, desired improved varieties of economically useful crops are raised by the technique of hybridization.

---