A store placed a large basket of fruit containing oranges and unripe bananas by the cash register. There were too many bananas to fit in the basket, so they put the rest in the back room. The next day, the bananas in the basket had ripened, but the ones in the back room had not. What is the most likely explanation?

Options

A. The heat in the store had accelerated the ripening process
B. The cytokinins in the oranges diffused into the bananas where the two fruits touched each other and triggered the bananas to ripen.
C. The auxin in the oranges diffused into the bananas where the two fruits touched each other and triggered the bananas to ripen.
D. The oranges had released ethylen into the air, which triggered the bananas to ripen.

Answer

### Step-by-Step Solution:

1. **Identify the Components**: The situation involves a basket of fruit containing oranges and unripe bananas, with some bananas stored in the back room.

2. **Observe the Conditions**: The bananas in the basket ripened overnight, while those in the back room did not. This indicates a difference in environmental conditions or exposure to certain substances.

3. **Understand the Role of Ethylene**: Ethylene is a plant hormone known to promote fruit ripening. It is released by certain fruits, including bananas and oranges.

4. **Analyze the Location of the Bananas**: The bananas in the basket were in close proximity to the oranges. This closeness likely allowed for the diffusion of ethylene gas released by the oranges, which would stimulate the ripening process in the bananas.

5. **Consider Other Factors**: The bananas in the back room were isolated from the oranges and thus did not receive any ethylene exposure, which explains why they remained unripe.

6. **Conclusion**: The most likely explanation for the ripening of the bananas in the basket is that the oranges released ethylene gas, which triggered the ripening process in the bananas.

### Final Answer:
The oranges had released ethylene into the air, which triggered the bananas to ripen.

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