Question

if the appositive in bold is nonrestrictive, set it off with commas. if it is restrictive, submit the text without making any changes. in september of 1522, the basque navigator juan sebastián elcano became the first ship commander to sail around the world.

Explanation:

The bolded "Juan Sebastián Elcano" is a nonrestrictive appositive: it provides extra, non-essential information about the already specific "Basque navigator" (we can identify the navigator without this name, so it needs commas to set it off).

Answer:

In September of 1522, the Basque navigator, Juan Sebastián Elcano, became the first ship commander to sail around the world.