What does a key signature specify?

• A. The tempo of the music.
• B. The time signature.
• C. The form and structure.
• D. The number and type of sharps or flats indicating the key.

Answer: (D)

Key signatures tell you which notes are consistently raised or lowered throughout the piece, establishing the tonal center and the scale you’re in. The number and type of sharps or flats indicate the key: for example, one flat points to F major or D minor, while three sharps point to A major or F# minor. Those symbols apply to every octave of the affected notes unless a natural sign inside a measure cancels them. They do not specify tempo, time signature, or form, which are separate ideas about speed, meter, and the structure of the music. So the key signature is really about which notes are altered regularly to define the key.