Let's analyze the words in the list to find the one that has a different sound in the underlined part:

1. **A. university** - /juː/
**B. unique** - /juː/
**C. unit** - /juː/
**D. undo** - /ʌ/
- **Different sound: D. undo** (/ʌ/ vs. /juː/)

2. **A. ground** - /aʊ/
**B. should** - /ʊ/
**C. about** - /aʊ/
**D. amount** - /aʊ/
- **Different sound: B. should** (/ʊ/ vs. /aʊ/)

3. **A. weather** - /ɛ/
**B. bread** - /ɛ/
**C. ahead** - /ə/
**D. mean** - /iː/
- **Different sound: D. mean** (/iː/ vs. /ɛ/ and /ə/)

4. **A. author** - /ɔː/
**B. other** - /ʌ/
**C. there** - /ð/
**D. breathe** - /iː/
- **Different sound: A. author** (/ɔː/ vs. /ʌ/, /ð/, and /iː/)

5. **A. excursion** - /ɜː/
**B. sunburst** - /ʌ/
**C. nurse** - /ɜː/
**D. picture** - /ɪ/
- **Different sound: D. picture** (/ɪ/ vs. /ɜː/ and /ʌ/)

To summarize:

1. D. undo
2. B. should
3. D. mean
4. A. author
5. D. picture

Each of these options has a different sound compared to the others in its respective group.