In the scenario provided, the aspect that shows a carbon source becoming a carbon sink is:
OB. decaying of the snake's remains
Explanation:
1. When the grass snake dies and its remains decay in the soil, it undergoes a process where the carbon from the snake's organic matter is stored in the soil.
2. This process of decay and carbon storage in the soil helps in removing carbon from the atmosphere, making it a carbon sink.
3. Over time, as more organic matter decays and gets stored in the soil, it contributes to the carbon sink effect by reducing the amount of carbon dioxide in the atmosphere.
4. On the other hand, burning fossil fuels like the processed remains of the snake releases carbon dioxide into the atmosphere, acting as a carbon source.
Therefore, the decaying of the snake's remains in the soil is the aspect of the scenario that demonstrates a carbon source becoming a carbon sink.