Sure! Here are the answers based on the pronunciation and stress differences:

### Questions 1-2 (Pronunciation)
1. **C** - "speaks" has a different ending sound compared to the others.
2. **C** - "habitat" has a different vowel sound in the second syllable compared to the others.

### Questions 3-4 (Stress)
3. **C** - "device" has the stress on the second syllable, while the others have stress on the first syllable.
4. **C** - "efficient" has stress on the second syllable, while "upmarket," "organic," and "drama" have stress on the first syllable.

Feel free to ask if you have any more questions!