Which ADDI metric best indicates that a candidate service boundary has high internal cohesion?

Think of it like working hands-on with IBM mainframe systems — the answer here is 'Programs in the cluster predominantly call each other rather than calling programs outside the cluster'. High cohesion means programs primarily interact with others in the same cluster. When most of a program's CALL statements reference other programs within the proposed boundary, the boundary has good i. On real mainframe exams, this concept comes up repeatedly so make sure you have it locked in.