Choose the correct set-up to demonstrate that $\text{CO}_2$ is given out during respiration:

To demonstrate that carbon dioxide ($\text{CO}_2$) is released during aerobic respiration, the experimental set-up must fulfill specific criteria:

1. Active Respiration: Germinating seeds must be used because they are actively growing and respiring at a high rate. Dry seeds (Option B) are dormant and will not produce measurable amounts of $\text{CO}_2$.
2. $\text{CO}_2$ Absorption: A small tube containing potassium hydroxide ($KOH$) must be suspended inside the airtight flask. $KOH$ absorbs the released $\text{CO}_2$ gas:

$$2KOH + \text{CO}_2 \rightarrow K_2\text{CO}_3 + \text{H}_2\text{O}$$

1. Pressure Drop: The absorption of $\text{CO}_2$ creates a partial vacuum (low pressure) inside the flask. This pressure difference forces water from the beaker to rise up the delivery tube.

• Set-up A contains germinating seeds and suspended $KOH$, which is the correct configuration.
• Set-up B uses dry seeds, which do not respire actively.
• Set-up C lacks $KOH$, so the released $\text{CO}_2$ is not absorbed, meaning no vacuum is created and the water level does not rise.
• Set-up D has incorrect placement of components, failing to maintain an airtight system.