The textbook provides direct answers for each case. In (a), displacing a spring sideways creates transverse motion, but the spring can also compress along its length, creating longitudinal waves. In (b), the piston's back-and-forth motion creates compressions and rarefactions in the liquid, which is characteristic of longitudinal waves. In (c), water surface waves (capillary and gravity waves) involve both transverse and longitudinal motion of water particles. In (d), ultrasonic waves in air are sound waves, and the context clearly states that 'air can sustain only longitudinal waves.'