The characteristic(s) common to urea, uric acid and ammonia is/are
(i). They are nitrogenous wastes.
(ii). They all need very large amount of water for excretion.
(iii). They are all equally toxic.
(iv). They are produced in the kidneys

Options

A. a) (i),(iii) and (iv)
B. b) (i) only
C. c) (i) and (iii)
D. d) (i) and (iv)

Explanation

To determine the characteristics common to urea, uric acid, and ammonia, we will analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Identify the Nature of the Compounds**:
- Urea, uric acid, and ammonia are all nitrogenous wastes produced during the metabolism of proteins and nucleic acids in organisms.

2. **Evaluate Statement (i)**:
- **Statement (i)**: "They are nitrogenous wastes."
- This statement is correct. All three compounds are indeed nitrogenous wastes.

3. **Evaluate Statement (ii)**:
- **Statement (ii)**: "They all need very large amounts of water for excretion."
- This statement is incorrect. Ammonia is highly toxic and requires a large amount of water for excretion. Urea requires a moderate amount of water, while uric acid requires very little water for excretion. Therefore, not all of them need large amounts of water.

4. **Evaluate Statement (iii)**:
- **Statement (iii)**: "They are all equally toxic."
- This statement is also incorrect. Ammonia is the most toxic, followed by urea, which is less toxic, and uric acid is the least toxic of the three. Hence, they are not equally toxic.

5. **Evaluate Statement (iv)**:
- **Statement (iv)**: "They are produced in the kidneys."
- This statement is incorrect. Urea and ammonia are primarily produced in the liver, while uric acid is also produced in the liver, with some production occurring in the kidneys. Therefore, not all of them are produced in the kidneys.

6. **Conclusion**:
- The only correct statement is (i): "They are nitrogenous wastes." Therefore, the answer is option B: 1 only.

### Final Answer:
The characteristic common to urea, uric acid, and ammonia is (i) They are nitrogenous wastes.

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