Some methods of determining the size of population are direct and indirect observations, sampling, and mark-and-recapture studies
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Sampling - Done by counting the animals in a small area and then estimating how many are in the larger area. You go out and take samples from different places so you can take the average. In most cases, it is not possible to count every member of a population so an estimate is made.
Mark and recapture - Another estimating method is a technique called "mark and recapture." This technique gets its name because some animals are first captured, marked, and released into the environment. Then another group of animals is captured. The number of marked animals in this second group indicates the population size.
Indirect observation - The members of a population may be small or hard to find. It may be easier to observe their tracks or other signs rather than the organisms themselves.
Direct observation - The most obvious way to determine the size of a population is to count, one by one.
B is unsustainable as this is a practice of intensive farming usually conducted indoors, and is resource and energy expensive. C is unsustainable because groundwater is a limited resource and groundwater can take 1000s of years to be recharged. D is unsustainable as this involves moving water across vast distances and is expensive and ecologically damaging. A is sustainable as drought-resistant plants would in the long run use less water.
The answer is bladder
The bladder stores urine and when the brain signals to release (when we have to go pee) it releases the urine through the urethra. The answer is not kidney because it doesn’t STORE the urine it filters waste and toxins in the body into the urine to be released from the body, the actual bladder itself is the organ that stores the urine in the body.
