Classification — specific sound-word vs general action: Identify the odd pair: Door : Bang, Piano : Play, Rain : Patter, Drum : Beat.

Introduction / Context:
Three pairs connect a source with a characteristic sound or sound-like action word (onomatopoeia or specific percussive verb). One pair instead connects an instrument to a very general action (“play”), not a distinctive sound-word. The solver must distinguish between “sound produced” vs “generic activity performed.”

Given Data / Assumptions:

• Door → Bang: characteristic sudden, loud sound associated with slamming.
• Rain → Patter: characteristic soft, repeated sound of raindrops.
• Drum → Beat: specific percussive action/sound term.
• Piano → Play: general activity rather than a specific sound-word (e.g., “plink,” “note,” “melody” would be closer to sound outcome).

Concept / Approach:
Look for pairs where the right-hand word names a distinct sound associated with the left-hand source. “Bang,” “patter,” and “beat” describe specific auditory events; “play” describes an action that could apply to many instruments and does not itself denote a sound type.

Step-by-Step Solution:
1) Door: “bang” is a signature sound → fits.2) Rain: “patter” is a signature sound → fits.3) Drum: “beat” is a signature percussive sound/action → fits.4) Piano: “play” is a generic activity verb, not a sound-word → odd.

Verification / Alternative check:
Try substituting other instruments: “violin : play,” “flute : play.” The pattern remains generic, proving that “play” does not uniquely characterize piano sound. By contrast, “patter,” “bang,” “beat” evoke immediate auditory imagery of their sources.

Why Other Options Are Wrong:
They map sources to distinctive, commonly accepted sound/action words.

Common Pitfalls:
Assuming any verb linked to an instrument counts. The question seeks specificity of sound, not merely an associated activity.

Final Answer:
Piano : Play