Final answer:
None of the given options represent properties of light that are directly proportional. Wavelength and frequency are inversely proportional as the speed of light is a constant; amplitude is independent of both frequency and speed.
Step-by-step explanation:
To address the question regarding which properties of light are directly proportional, we must refer to the fundamental relationships between wavelength, frequency, and speed of light. The speed of light (c) is a constant and is equal to the product of the wavelength (λ) and the frequency (ν) of light. This gives us the equation c = λν, indicating that wavelength and frequency are inversely proportional, not directly. For example, as the wavelength increases, the frequency decreases, and vice versa, keeping the speed of light constant.
Given the available choices:
A) Wavelength and frequency - These are inversely proportional.
B) Wavelength and speed - Speed of light is constant; wavelength does not influence it.
C) Frequency and amplitude - These properties are independent of each other.
D) Amplitude and speed - Amplitude is independent of speed.
Hence, none of the given options represent properties of light that are directly proportional. The correct relationship between wavelength and frequency is that they are inversely proportional.