Final answer:
The rich orebodies near Sudbury were formed due to an asteroid impact. This is supported by geological evidence such as shatter cones and the structure of the crater, as well as an abnormal concentration of iridium linked to extraterrestrial impacts.
Step-by-step explanation:
The rich orebodies near Sudbury formed as the result of an asteroid impact. This conclusion is supported by several lines of evidence, including the presence of shatter cones in the region, a geological structure indicative of an impact event, and the Sudbury structure itself, which is consistent with an impact crater. Additionally, the formation is associated with the unusual abundance of iridium, which is typically rare in the Earth's crust but more common in asteroids and is found in the Cretaceous-Paleogene boundary layer, further suggesting an extraterrestrial impact event. Findings from across the world, as discovered by Luis and Walter Alvarez, Frank Asaro, and Helen Michels, include a spike in the concentration of iridium within the sedimentary layer at the K-Pg boundary, pointing to asteroid impact as the cause of the K-Pg mass extinction.
Answer: a) an asteroid impact