Final answer:
The motif in question, composed of D, D flat, and B flat, is to be played pizzicato, where the performers pluck the strings of their instruments to create a unique sound.
Step-by-step explanation:
The three-note motif in the third measure of the second staff composed of D, D flat, and B flat is an example of a musical phrase typically played in an orchestral or chamber music setting. When performers are instructed to play this part "pizzicato"- plucking the strings, they are asked to pluck the strings of their instrument, usually a stringed instrument like a violin, viola, cello, or double bass, instead of using the bow. Playing pizzicato creates a distinctive, short, and often percussive sound that stands out within the texture of a musical piece, particularly when featured as a motif.