Read the dialog and answer the question.

Bella: Do you know how computers work?

Nessie: I don’t know. How do they work?

Bella: It has a ____ that connects all the parts of the computer to communicate with each other.

Nessie: Wow it’s awesome. Mother what? How do you spell that?

Bella: em – ou – ti – eij – i – ar – bi – ou – ei – ar – di.

Which correct word can complete the dialog?