In public urinals, the urine on standing gives a pungent smell, due to
or
State urine smells like ammonia because of
(a) Conversion of uric acid into ammonia by omithine cycle
(b) Conversion of both urea and uric acid into ammonia
(c) Conversion of urea into ammonia by bacteria
(d) None of these

Options

A. Conversion of uric acid into ammonia by omithine cycle
B. Conversion of both urea and uric acid into ammonia
C. Conversion of urea into ammonia by bacteria
D. None of these

Answer

To solve the question regarding the pungent smell of urine in public urinals, we will analyze the options provided and determine the correct answer step by step.

### Step-by-Step Solution:

1. **Understanding Fresh Urine**: Freshly excreted urine is typically sterile and has little to no smell. This is important to note as it sets the baseline for what happens when urine is left standing.

2. **Exposure to Air**: When urine is left standing, it is exposed to air. This exposure allows bacteria present in the environment to come into contact with the urine.

3. **Bacterial Action**: The bacteria that come into contact with the urine begin to act on the components of the urine, particularly urea. They break down urea into ammonia.

4. **Ammonia Production**: The conversion of urea into ammonia by bacteria is what leads to the pungent smell associated with standing urine. Ammonia has a strong, sharp odor, which is why it is noticeable.

5. **Evaluating the Options**:
- (a) Conversion of uric acid into ammonia by ornithine cycle: This is incorrect as the ornithine cycle is involved in the formation of urea, not the conversion of uric acid into ammonia.
- (b) Conversion of both urea and uric acid into ammonia: This is misleading because while urea is converted to ammonia, uric acid is not the primary component being converted in this context.
- (c) Conversion of urea into ammonia by bacteria: This is the correct option as it accurately describes the process that leads to the pungent smell.
- (d) None of these: This is incorrect since option (c) is valid.

6. **Conclusion**: Based on the analysis, the correct answer is (c) Conversion of urea into ammonia by bacteria.

### Final Answer:
(c) Conversion of urea into ammonia by bacteria.