Scientific knowledge and field technique are necessary to carryout
(I) Clonal selection (II) Pureline selection
(III) Hybridization (IV) Mass selection

Options

A. I & II
B. II & IV
C. II & III
D. I & IV

Answer

To solve the question regarding which techniques require scientific knowledge and field techniques among clonal selection, pureline selection, hybridization, and mass selection, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Clonal Selection**:
- Clonal selection involves selecting plants that are genetically identical to a parent plant. This technique is used to propagate desirable traits.
- **Hint**: Think about how identical genetic material is crucial for this method.

2. **Understanding Pureline Selection**:
- Pureline selection is a breeding method where plants are selected for their pure genetic lines, ensuring no variation within the selected plants.
- **Hint**: Consider the importance of genetic purity in breeding.

3. **Understanding Hybridization**:
- Hybridization is the process of crossing two different varieties to produce hybrids that may have desirable traits from both parents.
- **Hint**: Reflect on how combining different genetic traits requires scientific knowledge.

4. **Understanding Mass Selection**:
- Mass selection involves selecting a group of plants based on their phenotype, which may include high yield or disease resistance, without necessarily focusing on their genetic makeup.
- **Hint**: Think about how this method may not need deep scientific knowledge compared to the others.

5. **Identifying Techniques Requiring Scientific Knowledge**:
- Based on the definitions, both pureline selection and hybridization require a strong understanding of genetics and breeding techniques.
- **Hint**: Focus on the complexity of the genetic principles behind each method.

6. **Conclusion**:
- The techniques that require scientific knowledge and field techniques are **(II) Pureline selection** and **(III) Hybridization**.
- Therefore, the answer is **option C: 2 and 3**.

### Final Answer:
The techniques that require scientific knowledge and field techniques are Pureline selection (II) and Hybridization (III). Thus, the correct answer is option C: 2 and 3.