The erosional features shown in this image from Mars are thought to have been formed by: 
Definitions:
Normative Economics
A branch of economics that focuses on what ought to be or what should happen, often involving judgments and prescriptions for economic policy.
Positive Economics
A branch of economics that seeks to describe and explain the economy as it actually is, without making judgments about its effectiveness.
Judgments
Decisions or conclusions reached after consideration, often in a legal context or in personal assessment.
Empirical Economics
The branch of economics that focuses on using data and statistical methods to analyze and test economic theories.
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