How is 'strident' best characterized in terms of sound?

The term 'strident' is most accurately characterized as an unpleasantly loud and harsh sound. This adjective is often used to describe noises that are piercing or grating, which can evoke discomfort or annoyance when heard. In various contexts, such as music or speech, a strident tone lacks the pleasing qualities associated with softer or more harmonious sounds, making it particularly distinctive in its harshness.

The other choices present contrasting qualities that do not align with the nature of the word. For instance, 'soft and soothing' conveys a gentleness that strident sounds do not possess, while 'melodic and harmonious' suggests a level of pleasantness that is the opposite of what strident implies. Similarly, 'whispering and subtle' refers to quiet and understated sounds, further highlighting the distinct characteristics associated with strident sounds. Therefore, option C is the one that captures the essence of 'strident' most effectively.