Which of the following is a parameter of senescence or old age?

Options

A. The end of reproductive phase
B. Slowing of metabolism
C. The end of juvenile phase
D. Both (1) and (2)

Answer

To answer the question "Which of the following is a parameter of senescence or old age?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Senescence**:
- Senescence refers to the process of aging in organisms. It encompasses various physiological changes that occur as an organism transitions from youth to old age.

2. **Stages of Human Life**:
- Human life can be divided into several stages: birth, juvenile phase, reproductive phase, and old age (senescence).

3. **Reproductive Phase**:
- The reproductive phase in humans typically ends for females around the age of 45 to 50 years. This phase is characterized by the ability to reproduce and is crucial for the continuation of species.

4. **Metabolism Changes**:
- After the reproductive phase, significant changes occur in the body. One of the primary changes is a slowdown in metabolism. This means that the body's energy production and utilization become less efficient.

5. **Degradation of Body Functions**:
- As metabolism slows down, there is a degradation of bodily functions. This includes a decline in muscle strength, organ function, and overall vitality.

6. **Conclusion**:
- The parameters of senescence or old age include the end of the reproductive phase and the slowing of metabolism, which leads to the degradation of bodily functions.

7. **Final Answer**:
- Therefore, the correct answer to the question is that both the end of the reproductive phase and the slowing of metabolism are parameters of senescence. Hence, the answer is option number 4: both 1 and 2.