According to the Bohr effect for human Hemoglobin (HbA), the curves
reported below are compatible with:

The Bohr effect is valid for
Myoglobin and not for Hemoglobin.

None of the above

The black curve is at lower pH with respect to the red curve.

The black curve is at higher pH with respect to the red curve.

Both curves are compatible with the same pH value but different concentration of Hb.