Consider the following statements.
I. Photosynthesis uses `CO_2` that animals exhale as waste and generates `O_2` that animals inhale.
II. Nearly all the `O_2` in Earth's atmosphere has been released by photosynthesis processes.
Select the correct alternate.

Options

A. Only I
B. Only II
C. Both I and II
D. Neither I nor II

Answer

To solve the question, we need to analyze the two statements provided about photosynthesis and oxygen production.

### Step 1: Evaluate Statement I
**Statement I:** "Photosynthesis uses `CO_2` that animals exhale as waste and generates `O_2` that animals inhale."

- **Explanation:** During photosynthesis, plants take in carbon dioxide (`CO_2`) from the atmosphere. Animals exhale `CO_2` as a waste product of respiration. In the process of photosynthesis, plants convert `CO_2` and water into glucose and oxygen (`O_2`) using sunlight. Thus, this statement is correct.

### Step 2: Evaluate Statement II
**Statement II:** "Nearly all the `O_2` in Earth's atmosphere has been released by photosynthesis processes."

- **Explanation:** It is widely accepted that the majority of the oxygen in Earth's atmosphere is produced by photosynthesis, primarily by plants, algae, and cyanobacteria. While there are other processes that contribute to oxygen levels, such as photolysis of water in the atmosphere, photosynthesis is the primary source. Therefore, this statement is also correct.

### Step 3: Conclusion
Since both statements are correct, we can conclude that the correct answer is that both statements are true.

### Final Answer:
Both statements I and II are correct.