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

Input: Consider Input: Passage: A population is a group of individuals of the same species that live in the same area. The population is the unit of natural selection, adaptation, and microevolution. In ecology, how large a population is and how quickly it is growing are often used as measures of a species' health. Answer: population

Output: What term refers to a group of individuals of the same species that live in the same area and is the unit of natural selection, adaptation, and microevolution?

Input: Consider Input: Passage: Abrasion is another type of mechanical weathering. With abrasion, one rock bumps against another rock. Gravity causes abrasion as a rock tumbles down a slope. Moving water causes abrasion it moves rocks so that they bump against one another ( Figure below ). Strong winds cause abrasion by blasting sand against rock surfaces. Finally, the ice in glaciers cause abrasion. Pieces of rock embedded in ice at the bottom of a glacier scrape against the rock below. If you have ever collected beach glass or pebbles from a stream, you have witnessed the work of abrasion. Answer: mechanical

Output: What kind of weathering is abrasion?

Input: Consider Input: Passage: When the number of electrons and the number of protons are equal, the object is neutral. Answer: neutral
Output: When the number of electrons and the number of protons are equal, the object is what?