Which instrument is not typically part of a standard string quartet?

• A. Piano
• B. Violin
• C. Viola
• D. Cello

Answer: (A)

A standard string quartet is defined by four string instruments sharing the melodic and harmonic workload: two violins, a viola, and a cello. This pure string texture keeps balance and dialogue among four voices, each with a distinct role.

The piano isn’t typically part of that setup because it’s a keyboard instrument that can play many notes at once and sustain tones in ways that change the ensemble’s balance and texture. When a piano is included with strings, the ensemble is usually called a piano quartet (violin, viola, cello, and piano), not a standard string quartet. The other instruments listed—violin, viola, and cello—are the conventional members of the quartet.