Concept:The symbol /θ/ represents the voiceless "th" sound, as in "think" or "teeth".Explanation:The /θ/ sound is made without vibrating the vocal cords.Among the options, the word "stealthy" contains this voiceless /θ/ sound in its middle.The other words have the voiced /ð/ sound instead, like in "breathe", "wither", and "feather".So the correct word is "stealthy".Answer:C. stealthy