Ca n't be sure about that , though . One step at a time ... " Andy watched , fascinated , and did n't interrupt again . Castin worked with his laptop battery and the elevator 's wiring , cursing a lot as he went .
What was Castin doing ?
Pick the best answer from the following options:
- Working on the wiring .
 - Cursing his friend .
 - Buying a D battery .
 - Taking several steps at a time .


Working on the wiring .