instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: A drumlin is a long, low hill of sediments deposited by a glacier. Drumlins often occur in groups called drumlin fields. The narrow end of each drumlin points in the direction the glacier was moving when it dropped the sediments. Answer: a drumlin
answer:
What is the name of a long and low hill of sediments which have been deposited by a glacier?

question:
Passage: Acidity is measured on a pH scale. Rain that is 5.0 or less on that scale is considered acid rain. Answer: ph scale
answer:
Acidity is measured on what kind of scale?

question:
Passage: Sedimentary rocks are very useful for determining the deformation history of an area. Answer: sedimentary
answer:
What type of rocks are very useful for determining the deformation history of an area?