Correct Answer: C — Good internal consistency reliability

Cronbach's Alpha (\(\alpha\)) measures the internal consistency of a multi-item scale — the degree to which items within the scale measure the same construct.

Interpretation benchmarks:

Cronbach's \(\alpha\)	Internal Consistency
\(\alpha \geq 0.90\)	Excellent
\(0.80 \leq \alpha < 0.90\)	Good
\(0.70 \leq \alpha < 0.80\)	Acceptable
\(0.60 \leq \alpha < 0.70\)	Questionable
\(\alpha < 0.60\)	Poor — tool needs revision

\(\alpha = 0.87\) falls in the 'Good' range, meaning the 20 items are cohesively measuring the same concept. Cronbach's Alpha measures reliability, not validity — a distinction critical for Head Nurse research appraisal.