Based on the provided IPA notations, here are the answers:
1. A. balanced, B. yoga, C. fatty, and D. natural all have the same underlined part (the 'a' sound is the same in these four words: ˈbælənst, ˈjoʊgə, ˈfæti, and ˈnæʧərəl, which is /æ/), but only one word stands out as having a different vowel sound, "yoga" has /oʊ/. So the correct answer is B. yoga.
2. A. change, B. poaching, C. chemical, and D. achievement all have the same underlined part (the 'ch' sound is the same in these four words: ʧeɪnʤ, ˈpoʊʧɪŋ, ˈkɛmɪkəl, and əˈʧivmənt), but only one word stands out as having a different stress pattern and vowel sound. The correct answer is A. change.
3. A. fresh, B. diet, C. flesh, and D. exercise all have different vowel sounds (frɛʃ, daɪət, flɛʃ, and ˈɛksərsaɪz), but the 'e' sound is the same in three of these words, the odd one out is D. exercise.
4. A. soda, B. fatty, C. balance, and D. habit all have the same underlined part (the 'a' sound is the same in three of these four words: ˈsoʊdə, ˈfæti, and ˈbæləns), but only one word stands out as having a different vowel sound, the odd one out is D. habit, which is actually incorrect since habit has the same 'a' sound. So the correct answer is A. soda.
5. A. ache, B. chip, C. choose, and D. cheese all have the same underlined part (the 'ch' sound is the same in three of these four words: ʧɪp, ʧuz, and ʧiz), but only one word stands out as having a different consonant sound. The correct answer is A. ache.
6. A. medicine, B. energy, C. exercise, and D. obesity all have the same underlined part (the 'e' sound is the same in three of these four words: ˈmɛdəsən, ˈɛnərʤi, and ˈɛksərsaɪz), but only one word stands out as having a different stress pattern and vowel sound, the odd one out is D. obesity.