D 7/C
The D 7 chord consists of the D (Perfect unison), F# (Major third), A (Perfect fifth) and C (Minor seventh) notes, with C as the bass note.

How to play the D 7/C chord
- Play C as the lowest bass note in the left hand
- Find D (Root) on the piano keyboard
- Add F# (Major third) — 4 semitones above D
- Add A (Perfect fifth) — 7 semitones above D
- Add C (Minor seventh) — 10 semitones above D
- Press all 5 notes simultaneously to sound the D 7/C chord