What are the tonic, subdominant, and dominant triads of required keys in?

The tonic, subdominant, and dominant triads are fundamental components of Western music harmony, and they can be represented in various forms. The correct choice indicates that these triads can exist in both root position and inversions, which enriches their usage within musical contexts.

In music theory, a root position triad comprises the root note as the lowest pitch, while inversions rearrange the notes so that either the third or the fifth of the triad becomes the lowest pitch. This flexibility allows composers and musicians to create different harmonic progressions and voice leading, thus enhancing the expressiveness of the music.

This broader range of presentation also reflects the varying contexts in which these triads can be used, such as during modulation, progression, or when creating tension and resolution within a piece. Tonic, subdominant, and dominant functions are often used in sequence; having the ability to play them in both root and inverted forms allows for more dynamic and varied musical expression.

The other options, while reflecting different ways triads can be structured, limit the harmonic application and exploration that root positions and inversions provide. For instance, saying "only broken form" excludes solid chords entirely—this restrictiveness would miss the rich harmonic textures possible in compositions