the distance from the peak to a peak of a successive wave.

Wavelength

Explanation:

Wavelength is defined as the distance between two successive wave crests or troughs. The crests are high points while the troughs are low points of a wave. The above definition as the distance from the peak to a peak of a successive wave fits the definition of wavelength. Wavelength is directly proportional to the speed of wave since speed is the product of wavelength and frequency. Therefore, when the wavelengths are short, the speed also reduces.

answer; /// the above statement is (true);