The D minor chord i is the D minor chord, and contains the notes D, F, and A. This tonic chord's root / starting note is the 1st note (or scale degree) of the D natural minor scale. The roman numeral for number 1 is 'i' and is used to indicate this is the 1st triad chord in the scale.
Explanation:
The D minor chord III is the F major chord, and contains the notes F, A, and C. This mediant chord's root / starting note is the 3rd note (or scale degree) of the D natural minor scale
