Extrinsic factors affecting the development include all except

Options

A. `O_2`, light, temperature
B. `CO_2` and nutrients
C. Water
D. PGRs and genetic factors

Answer

To solve the question "Extrinsic factors affecting the development include all except," we need to identify which of the provided options is not an extrinsic factor affecting plant development.

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Extrinsic Factors**: These are external environmental factors that affect plant growth and development. Examples include light, temperature, water, oxygen (O2), carbon dioxide (CO2), and nutrient availability in the soil.
- **Intrinsic Factors**: These are internal factors related to the plant itself, such as genetic makeup and plant growth regulators (PGRs or hormones).

2. **Analyze the Options**:
- We need to evaluate each option to determine if it is an extrinsic factor or not.
- **Option 1**: O2, light, and temperature - All these are external factors affecting plant growth.
- **Option 2**: CO2 and nutrients - Both are also external factors that influence plant development.
- **Option 3**: Water - Water is an essential external factor for plant growth.
- **Option 4**: PGRs and genetic factors - These are internal factors (intrinsic) and do not belong to the category of extrinsic factors.

3. **Identify the Correct Answer**:
- Since options 1, 2, and 3 are all extrinsic factors, and option 4 (PGRs and genetic factors) is not, the correct answer is **Option 4**.

### Final Answer:
Extrinsic factors affecting the development include all except **PGRs and genetic factors**.

---