The notes are changing as follows:
- From E to D-sharp: This is a half step down.
- From F to F-sharp: This is a half step up.
- From G to A-flat: This is also a half step, but in this case, it is a half step up (moving from G to A-flat is the same as moving up a half step since A-flat is a semitone above G).
Overall, the changes consist of a mixture of half steps.
Therefore, the best response from the options provided is: by a mixture of whole and half steps.