Ware bare.

The question asks you to find the sound that is different from others. The sound /t/ is voiceless, meaning you make it without vibrating your vocal cords.

The other sounds are all voiced. When you say /b/, /d/, and /f/, your throat vibrates. But /t/ is made with just air, no vibration.

Understanding voiced and voiceless sounds helps you pronounce words correctly. Try touching your throat when you say these sounds to feel the difference.