By looking at a plant externally can you tell whether a plant is `C_(3) or C_(4)` ? Why and how?

Explanation

### Step-by-Step Solution:

1. **Understanding C3 and C4 Plants**:
- C3 and C4 plants are two different types of plants that use different pathways for photosynthesis. C3 plants primarily use the Calvin cycle, while C4 plants have a modified pathway that allows them to efficiently fix carbon dioxide in high-temperature environments.

2. **External Characteristics**:
- When observing a plant externally, it is challenging to determine whether it is a C3 or C4 plant based solely on its appearance. Both types can have similar morphological features, such as leaf shape, size, and color.

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