A teacher–student relationship should be cordial, respectful, and professionally bounded.
Why C fits: Respect supports trust and communication while preserving the teacher’s professional responsibilities.
Why the others are weaker: Excessive intimacy can blur boundaries; limiting all contact to formal classroom exchanges may prevent needed support; indifference damages learning.
In practice: Listen to students, treat them fairly, maintain appropriate boundaries, and use school support systems when a concern needs specialised help.