Read the following context and choose the best option to answer the question.
Context: 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 .
Question: Why is Castin so frustrated that he is reduced to cursing ?
Options: 
A. Castin is unable to stop getting mad at others .
B. Castin is unable to fix the clock .
C. Castin is unable to empathize with others .
D. Castin is unable to understand the electronics .


D