What is the key signature of the A Major scale?

The key signature of the A Major scale contains three sharps. In Western music theory, each major scale has a specific pattern of whole and half steps, and the arrangement of sharps and flats in its key signature is determined by that scale's construction.

For the A Major scale, which is derived from the pattern of whole and half steps: whole, whole, half, whole, whole, whole, half, the notes in this scale are A, B, C#, D, E, F#, and G#. The sharps in the key signature correspond to the notes C, F, and G. Therefore, the use of three sharps (F#, C#, and G#) not only defines the A Major scale but also indicates the tonal center being on A.

While the other choices reflect different key signatures associated with other major scales, they do not align with the specific characteristics of the A Major scale. Examining their relationship to the circle of fifths can clarify their distinct signatures further.