Answer:
D. frequency, because there are more crests in the same length of rope than there are in the other waves
Explanation:
Wave frequency is defined as the number of waves passing a fixed point at a given time.
Wave frequency is highly influenced by the number of crests in the wave that pass the fixed point in 1 second. It means, more is the number of crests in the same length of rope, the higher will be the wave frequency.
Wave 2 has a maximum number of crests and thus wave 2 has the greatest wave frequency in comparison to other ropes.
Hence, the correct answer is "D".