C

Step 1: Identify the wavelength provided in the image, which is 1 nm (nanometer).
Step 2: Understand the electromagnetic spectrum. The classification of electromagnetic waves based on wavelength is as follows:
- Radio waves: > 1 mm
- Microwaves: 1 mm to 1 m
- Infrared: 700 nm to 1 mm
- Visible light: 400 nm to 700 nm
- Ultraviolet: 10 nm to 400 nm
- X-rays: 0.01 nm to 10 nm
- Gamma rays: < 0.01 nm
Step 3: Since 1 nm falls within the range of x-rays (0.01 nm to 10 nm), it indicates that the light wavelength given belongs to x-rays.
Therefore, the correct answer is C.