Given a scientific passage and an answer, generate a question for the given answer.

Example Input: Passage: When you use a machine, you apply force to the machine. This force is called the input force. The machine, in turn, applies force to an object. This force is called the output force. The output force may or may not be the same as the input force. The force you apply to the machine is applied over a given distance, called the input distance. The force applied by the machine to the object is also applied over a distance, called the output distance. The output distance may or may not be the same as the input distance. Answer: output force
Example Output: What do you call the force a machine applies to an object?

Example Input: Passage: Pollination by Insects Bees are perhaps the most important pollinator of many garden plants and most commercial fruit trees (Figure 32.12). The most common species of bees are bumblebees and honeybees. Since bees cannot see the color red, bee-pollinated flowers usually have shades of blue, yellow, or other colors. Bees collect energy-rich pollen or nectar for their survival and energy. Answer: pollination
Example Output: What important function do bees perform on garden plants and many commercial fruit trees?

Example Input: Passage: Fertilizer in runoff leads to algal blooms and dead zones in bodies of water. This type of pollution is called nonpoint-source pollution. Point-source pollution includes waste water from factories and sewage treatment plants. Hot water discharge causes thermal pollution. Answer: excess of fertilizers and other nutrients
Example Output:
What causes eutrophication to occur?