Final answer:
The closest frequencies to 500 Hz that an average person can clearly distinguish are those that differ by at least 0.3% or 1.5 Hz from 500 Hz. Therefore, frequencies of 498.5 Hz and 501.5 Hz would be discernible as different from 500 Hz for most people, making option d) the closest correct answer among the given choices.
Step-by-step explanation:
The question pertains to the ability of the average human to distinguish between different sound frequencies, specifically those closest to 500 Hz. The concept in question is known as pitch perception, which relates to our ability to perceive the frequency of a sound. According to the information provided, humans can typically distinguish between sounds if their frequencies differ by 0.3% or more. Thus, for a sound of 500 Hz, the closest frequencies that can be distinguished from it would be 500 Hz × 0.003, which is 1.5 Hz. Therefore, we would have 500 Hz - 1.5 Hz = 498.5 Hz and 500 Hz + 1.5 Hz = 501.5 Hz, which means that option d) 498 Hz and 502 Hz is the closest to the correct answer from the choices presented. However, it is important to note that some individuals may be able to discern even smaller frequency differences due to individual differences in pitch perception abilities.