Which one of the following aspects is a exlusive characteristic of living things?

Options

A. Perception of events happening in the environment and their memory
B. Increase in mass by accumulation of material both on surface as well as internally
C. Isolated metabolic reactions occur in-vitro
D. Increase in mass from inside only

Answer

To solve the question regarding which aspect is an exclusive characteristic of living things, we can analyze the provided options step by step.

### Step-by-Step Solution:

1. **Understanding the Options**:
- **Option A**: Perception of events happening in the environment and their memory.
- **Option B**: Increase in mass by accumulation of material both on the surface as well as internally.
- **Option C**: Isolated metabolic reactions occurring in vitro.
- **Option D**: Increase in mass from inside only.

2. **Analyzing Option A**:
- This option refers to the ability of living organisms to perceive their environment and retain memories. This characteristic is often associated with consciousness or irritability, which is unique to living beings.

3. **Analyzing Option B**:
- This option talks about the increase in mass by accumulation of materials. However, this process is not exclusive to living organisms. Non-living entities, such as crystals, can also increase in mass through accumulation.

4. **Analyzing Option C**:
- This option mentions isolated metabolic reactions occurring in vitro. While metabolic reactions are indeed a characteristic of living organisms, they can also be replicated in laboratory settings (in vitro), which means they are not exclusive to living beings.

5. **Analyzing Option D**:
- This option refers to an increase in mass from inside only. Similar to Option B, this process can occur in non-living entities as well, making it not exclusive to living things.

6. **Conclusion**:
- After analyzing all the options, it is clear that **Option A** (Perception of events happening in the environment and their memory) is the only aspect that is exclusive to living things. This characteristic is tied to consciousness and the ability to respond to stimuli, which is not found in non-living entities.

### Final Answer:
The exclusive characteristic of living things is **Perception of events happening in the environment and their memory**.