Complete the following sentence by selecting the correct option.
Receptors associtated with aortic arch and carotid artery can recognise changes in `overset((i))"______"` and `overset((ii))"______"` concentration and send necessary signals to `overset((iii))"______"` for remedial actions.

Options

A. `{:("(i)",(ii),(iii)),(O_(2),CO_(2),"pneumotaxic centre"):}`
B. `{:("(i)",(ii),(iii)),(CO_(2),H^(+),"rhythm centre"):}`
C. `{:("(i)",(ii),(iii)),(CO_(2),H^(+),"apneustic centre"):}`
D. `{:("(i)",(ii),(iii)),(O_(2),H^(+),"pneumotaxic centre"):}`

Explanation

To complete the sentence based on the information provided, we will analyze the roles of receptors associated with the aortic arch and carotid artery in recognizing changes in gas concentrations and sending signals for remedial actions.

### Step-by-Step Solution:

1. **Identify the receptors' location and function**:
- The receptors associated with the aortic arch and carotid artery are known as peripheral chemoreceptors. They play a crucial role in monitoring the chemical composition of the blood.

2. **Determine what these receptors detect**:
- These receptors primarily respond to changes in the concentrations of gases in the blood. The two main gases they monitor are carbon dioxide (CO₂) and oxygen (O₂).
- Additionally, they are sensitive to changes in pH, which is related to hydrogen ion (H⁺) concentration.

3. **Select the correct gas concentrations**:
- The receptors are sensitive to an increase in carbon dioxide levels and a decrease in pH (which corresponds to an increase in H⁺ ions). Therefore, the first blank should be filled with "carbon dioxide" and the second blank with "H plus ion".

4. **Identify where the signals are sent**:
- The signals from these receptors are sent to the respiratory rhythm center, which is located in the medulla oblongata of the brain. This center is responsible for regulating the rate and depth of breathing.

5. **Complete the sentence**:
- The completed sentence is: "Receptors associated with aortic arch and carotid artery can recognize changes in **(i) carbon dioxide** and **(ii) H plus ion** concentration and send necessary signals to **(iii) rhythm center** for remedial actions."

### Final Answer:
- (i) carbon dioxide
- (ii) H plus ion
- (iii) rhythm center