Widmanstätten Patterns Uniquely Identify Samples as Iron Meteorites

Multiple Choice

Widmanstätten patterns uniquely identify samples as iron meteorites. Why is this?

A) These patterns require iridium, which is common in iron meteorites but is rare on Earth.
B) Widmanstätten patterns are radioactive.
C) These patterns involve crystals, which only form after millions of years of slow cooling.
D) These patterns are actually cracks in the structure of the meteorite that form only when an iron meteorite becomes heated during its passage through Earth's atmosphere.