In a note tree, if you add up the durations from left to right on any level, you typically end up with a whole note. This is because, in music notation, different note values add up to create larger values, and commonly all subdivisions at a given level will sum up to a whole.
For example:
- Four quarter notes equal one whole note.
- Two half notes equal one whole note.
- Eight eighth notes equal one whole note.
Therefore, the correct answer is a whole note.