Growth in plant can be measured by

Options

A. arc auxanometer
B. pfeffer's auxanometer
C. direct method
D. all of these

Answer

To answer the question "Growth in plants can be measured by," we can follow these steps:

### Step-by-Step Solution:

1. **Identify Measurement Instruments**:
- The first step is to recognize the different instruments that can be used to measure plant growth. The video mentions three specific methods: arc oximeter, pfizer oximeter, and direct method.

2. **Understand the Arc Oximeter**:
- The arc oximeter is an instrument designed to measure plant growth based on length. It operates using a thread that runs over a pulley, with one end attached to the tip of the plant and the other end connected to a weight. The deflection of a needle indicates the growth of the plant.

3. **Understand the Pfizer Oximeter**:
- Although the video does not elaborate much on the pfizer oximeter, it is another instrument that assists in measuring plant growth. It likely functions similarly to the arc oximeter, providing quantitative data on growth.

4. **Understand the Direct Method**:
- The direct method involves measuring the growth of a plant by comparing its length at different times. This method allows for a straightforward assessment of how much a plant has grown over a specific period. It is often referred to as the comparison method.

5. **Conclusion**:
- Since all three methods (arc oximeter, pfizer oximeter, and direct method) can be used to measure plant growth, the correct answer to the question is "all of the above."

### Final Answer:
Growth in plants can be measured by:
- Arc oximeter
- Pfizer oximeter
- Direct method
- Therefore, the correct answer is **all of the above**.

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