The correct option is A Sound will be louder but pitch will not be different.
How the brain interprets the frequency of an emitted sound is called the pitch. The faster the vibration of the source, the higher is the frequency and the higher is the pitch. The loudness or softness of a sound is determined basically by its amplitude. The amplitude of the sound wave depends upon the force with which an object is made to vibrate.
Therefore, if we struck a piano hard, the sound will be louder, but the pitch remains same, since the frequency does not change.