In the following passage there are blanks, each of which has been numbered. Select the correct option to fill in the blanks. The seemingly ___1______ hummingbird is one of the toughest beasts in the animal kingdom. Some 330 species ___2_____in diverse and often brutal environments. Mysteriously, the birds are found only in North and South America. ‘They’re living ____3____the edge of what’s possible for vertebrates, and they’re mastering it,’ says Karl Schuchmann, a German_____4_____, who studied a captive hummer that lived 17 years. ‘Imagine the _____5______of an organism of only five or six grams to live that long,’ he says.