Question

the main, or central, idea of the passage is the greenlanders mysterious iron mountain was eventually revealed to be three large meteorites. how does the detail in bold develop the main idea?

when british explorer sir john ross encountered inuit greenlanders wielding iron tools in 1818, he was mystified; after all, they did not have the technology to extract iron from ore. they told ross that their iron source was a saviksoah—an \iron mountain\—but refused to disclose its location. scientists back in britain partially solved the puzzle by analyzing some of the tools and determining that they likely came from a meteorite. subsequently, several other explorers attempted, and failed, to confirm the sources existence. in 1894, however, american explorer robert peary had better luck. the inuits were now obtaining iron through trade; they no longer needed the iron mountain and were willing to reveal it. a guide led peary to three meteorites, which are currently housed in new yorks american museum of natural history. the most massive, called ahnighito, weighs thirty tons and is the largest meteorite in any museum.

it suggests that the guide, not peary, should receive credit for the discovery.
it confirms an initial hypothesis about the source of the iron.
it contrasts the inuits story with the scientific explanation of the iron.

Explanation:

The main idea is that Greenlanders' "iron mountain" was three meteorites. Earlier, British scientists hypothesized the iron came from a meteorite. The bolded detail shows Peary found the meteorites, which proves that initial scientific hypothesis correct. The other options are incorrect: the text does not focus on giving credit to the guide, and it does not contrast the Inuits' story but instead confirms the scientific explanation for their iron source.

Answer:

It confirms an initial hypothesis about the source of the iron.