Led by Syrian American astronomer Shadia Habbal, the Solar Wind Sherpas are an intrepid team of scientists who travel the globe to study solar winds, the streams of particles emanating from the Sun that are only visible from certain locations during a total solar eclipse. When such an eclipse is imminent, the Sherpas pack up their telescopes and ________ ready.

Which choice completes the text so that it conforms to the conventions of Standard English?