How is the term "strident" best described?

The term "strident" is best described as harsh and grating. It is often used to characterize sounds that are loud, discordant, and difficult to listen to, typically conveying a sense of intensity or aggressiveness. This description captures the essence of the word, as it suggests a lack of pleasantness or harmony in the sound, making it jarring to the ears.

In contrast, the other choices depict qualities that are antonymous to "strident." Soft and soothing imply a gentle and comforting nature, while quiet and subtle suggest a lack of intensity that does not align with the loudness implied by "strident." Gentle and mild also connote a softness that is opposite to the harshness of the term. Thus, "harsh and grating" accurately reflects the essence of "strident."