The correct answer is D) Longitudinal.
In fact, when the tuning fork is hit, it starts to vibrate. Its vibration is transmitted to the surrounding air, creating an alternating pattern of regions of compression (higher pressure) and rarefaction (lower pressure). These regions then move away from the tuning fork, transporting the sound wave. Since the particles of air, in this case, move back and forth along the direction of propagation of the wave, this is a longitudinal wave.