Here are the answers to the questions based on the pronunciation of the underlined parts:

1. **B. sugar** - The "u" in "sugar" differs from the "u" sound in "put," "butter," and "push."
2. **C. leftover** - The "e" in "leftover" differs from the "e" sound in "decompose," "eco-friendly," and "butter."
3. **D. biological** - The "bi" in "biological" differs from the "ch" sound in "childhood," "biography," and "marriage."
4. **D. army** - The "ar" in "army" differs from the "a" sound in "admire," "achievement," and "adopt."
5. **D. military** - The "mil" in "military" differs from the "cam" in "campaign," "diary," and "biography."

So the answers are:
1. B
2. C
3. D
4. D
5. D