To solve the problem, we need to determine the total amount of urine excreted per day by humans.
1. Normal Urine Excretion:
On average, a healthy adult human excretes about 1.5 liters of urine per day. The amount can vary based on factors like hydration, diet, and overall health, but the typical range is between 1.0 to 2.0 liters per day.
2. Given Options:
- Option (A): 1.0 - 1.2 liters is on the lower end of the typical range.
- Option (B): 1.2 - 1.4 liters is a reasonable range.
- Option (C): 1.4 - 1.6 liters is consistent with average daily excretion.
- Option (C): 1.6 - 1.8 liters is also within the normal range for most adults.
3. Final Answer:
The total amount of urine excreted per day by humans is about $ \mathbf{1.6 - 1.8} $ liters.