The correct answer is four eighth notes.
A quarter note is equal to two eighth notes, so four eighth notes together would equal one quarter note.
To clarify:
- A dotted quarter note is worth three eighth notes, so two dotted quarter notes would be worth six eighth notes.
- Two half notes are worth four quarter notes (or eight eighth notes).
- Four sixteenth notes equal one half note, so it would take eight sixteenth notes to equal one quarter note.
Therefore, four eighth notes is the correct answer.