Concept:The symbol /θ/ represents the voiceless dental fricative sound, as in the 'th' of "thin".Explanation:The 'th' spelling can produce two different sounds: voiced /ð/ and voiceless /θ/.In "feather", "wither", and "breathe", the 'th' is pronounced as voiced /ð/.In "stealthy", the 'th' has the voiceless /θ/ sound.Therefore, "stealthy" is the correct answer.Answer:D. stealthy