The relative minor of a major key is the minor key that shares the same key signature. In this case, C major and A minor share the same key signature of no sharps or flats, so A minor is the relative minor of C major.

The circle of fifths is a way of organizing the 12 major keys in a logical order. Starting with the key of C major, each key to the right is a perfect fifth above the previous key. This means that the keys on the circle of fifths are: C, G, D, A, E, B, F#, C#, G#, D#, A#, and F.

The relative major of a minor key is the major key that shares the same key signature. In this case, A minor and C major share the same key signature of no sharps or flats, so C major is the relative major of A minor.

The key signature for the key of G major is one sharp, which is F#. This is because the G major scale contains the notes G, A, B, C, D, E, and F#, and the F# is the only note that is not in the C major scale.

The key signature for the key of D minor is one flat, which is Bb. This is because the D minor scale contains the notes D, E, F, G, A, Bb, and C, and the Bb is the only note that is not in the C major scale.

The tonic note of a key is the first note of the scale. In the case of F major, the first note of the scale is F, so F is the tonic note.

The tonic note of a key is the first note of the scale. In the case of B minor, the first note of the scale is B, so B is the tonic note.

The interval between the tonic and the dominant in a major scale is a perfect fifth. This is because the dominant is the fifth note of the scale, and a perfect fifth is the interval between two notes that are five steps apart.

The interval between the tonic and the subdominant in a minor scale is a perfect fourth. This is because the subdominant is the fourth note of the scale, and a perfect fourth is the interval between two notes that are four steps apart.

The parallel minor of a major key is the minor key that has the same tonic note. In this case, the tonic note of A major is A, so the parallel minor of A major is A minor.

The parallel major of a minor key is the major key that has the same tonic note. In this case, the tonic note of E minor is E, so the parallel major of E minor is E major.

The leading tone in a major key is the seventh note of the scale. In the case of C major, the seventh note of the scale is B, so B is the leading tone.

The leading tone in a minor key is the seventh note of the scale raised by a half step. In the case of G minor, the seventh note of the scale is F, and raising it by a half step gives us F#, so F# is the leading tone.

The enharmonic equivalent of a note is another note that sounds the same, but is written differently. In the case of C#, the enharmonic equivalent is Db, because both notes sound the same.

The enharmonic equivalent of a note is another note that sounds the same, but is written differently. In the case of Gb, the enharmonic equivalent is F#, because both notes sound the same.