In the context of the sentence, "It is the International Space Station (ISS), and for the decade that it has been in operation, it has been the temporary home of astronauts from around the globe," the word "operation" refers to the functioning or working condition of the International Space Station.
Given that context, the appropriate definition from the dictionary would likely be:
B. definition 2 (which typically pertains to the functioning or activity of a system or machinery).
However, without the specific definitions provided in the dictionary entry, I cannot confirm which number it corresponds to definitively. But based on context, it pertains to the period during which the ISS has been functioning.