Assertion : Metabolism refers to the sum of chemical reaction that occur within living organisms.
Reason : Metabolic reactions occur simultaneously inside living organisms.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To analyze the given assertion and reason, we can break down the solution into the following steps:

### Step 1: Understand the Assertion
The assertion states that "Metabolism refers to the sum of chemical reactions that occur within living organisms." This means that metabolism encompasses all the biochemical processes that take place in an organism, including both the breakdown of substances (catabolism) and the building up of substances (anabolism).

### Step 2: Understand the Reason
The reason states that "Metabolic reactions occur simultaneously inside living organisms." This implies that many different metabolic processes happen at the same time within an organism, which is true as various biochemical pathways operate concurrently to maintain life.

### Step 3: Evaluate the Truth of the Statements
- **Assertion**: True. Metabolism indeed refers to all the chemical reactions that occur in living organisms.
- **Reason**: True. It is accurate to say that metabolic reactions occur simultaneously in living organisms.

### Step 4: Determine the Relationship Between Assertion and Reason
While both the assertion and the reason are true, the reason does not provide a correct explanation for the assertion. The assertion defines what metabolism is, while the reason describes a characteristic of metabolic processes but does not explain why metabolism is defined as the sum of these reactions.

### Conclusion
Both the assertion and reason are true, but the reason is not the correct explanation of the assertion. Therefore, the correct answer is that both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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