Answer:
A a Transverse wave.
Step-by-step explanation:
A transverse wave is said to be generated whenever the particles of a medium vibrate in a direction perpendicular to the direction of motion of the wave.
When the picnic blanket is shaken the particles of air (the medium in this case) will move up and down and the transverse wave travels along the blanket , at right angles to the up and down motion of the particles.