Complete the following sentence by selecting the correct option.
the breathing rhythm is generated in the `overset((i))"______"` and is influenced by variation in levels of `overset((ii))"______"` in the blood.

Options

A. `{:("(i)",(ii)),("medulla",CO_(2)):}`
B. `{:("(i)",(ii)),("medulla",O_(2)):}`
C. `{:("(i)",(ii)),("frontal lobe",CO_(2) and O_(2)):}`
D. `{:("(i)",(ii)),("frontal lobe",CO_(2)):}`

Explanation

To complete the sentence, we need to identify the correct parts that fill in the blanks regarding the generation of breathing rhythm and the factors influencing it.

1. **Identify where the breathing rhythm is generated**:
- The breathing rhythm is primarily generated in the **medulla oblongata**, which is a part of the brain responsible for autonomic functions, including breathing.

2. **Identify what influences the breathing rhythm**:
- The breathing rhythm is influenced by the levels of **carbon dioxide (CO2)** in the blood. An increase in carbon dioxide levels leads to a decrease in blood pH, which stimulates the respiratory center in the medulla to adjust the breathing rate accordingly.

Putting it all together, we can complete the sentence:

"The breathing rhythm is generated in the **medulla** and is influenced by variation in levels of **carbon dioxide** in the blood."

### Final Answer:
The breathing rhythm is generated in the **medulla** and is influenced by variation in levels of **carbon dioxide** in the blood.

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