Step 1: Map competencies to professional standards.
Effective practice requires technical competence (theory, methods, ethics), keen observation to pick up verbal/non-verbal cues, and interpersonal sensitivity to build rapport, show empathy, and minimize bias.
Step 2: Integrate for effectiveness.
These abilities work together: observation feeds assessment; sensitivity improves validity of data and compliance; competence ensures evidence-based intervention.
Step 3: Conclude.
Because all three are essential hallmarks, All of these is correct.
\[
\boxed{\text{Option D}}
\]