Sure, here are the answers to the pronunciation differences:

1. A. protection (The underlined part "pro" is pronounced differently compared to "con" in control, "pol" in pollution, and "for" in forest)
2. D. giant (The underlined part "gi" is pronounced differently compared to "bio" in biodiversity, "cli" in climate, and "go" in gorilla)
3. C. flood (The underlined part "oo" is pronounced differently compared to "oo" in book, look, and good)
4. A. nature (The underlined part "na" is pronounced differently compared to "ma" in manage, "ba" in balance, and "ca" in campfire)
5. C. sustain (The underlined part "sus" is pronounced differently compared to "cul" in culture, "pub" in public, and "but" in butterfly)
6. A. flow (The underlined part "fl" is pronounced differently compared to "mo" in modern, "pro" in project, and "on" in online)
7. A. distract (The underlined part "dis" is pronounced differently compared to "tab" in tablet, "stra" in strategy, and "ex" in exchange)
8. B. schedule (The underlined part "sch" is pronounced differently compared to "im" in immediate, "bl" in blended, and "le" in lesson)
9. D. modern (The underlined part "mo" is pronounced differently compared to "fo" in focus, "con" in control, and "ro" in role)
10. A. recording (The underlined part "re" is pronounced differently compared to "ed" in educate, "ch" in children, and "de" in device)
11. D. respiratory (The underlined part "re" is pronounced differently compared to "go" in gorilla, "en" in environment, and "con" in consequence)
12. A. tortoise (The underlined part "tor" is pronounced differently compared to "eco" in ecosystem, "bio" in biodiversity, and "pro" in promotion)
13. D. respiratory (The underlined part "re" is pronounced differently compared to "id" in identify, "pr" in practical, and "ha" in habitat)
14. A. extreme (The underlined part "ex" is pronounced differently compared to "ex" in excellent, "ex" in execute, and "ex" in exercise)
15. A. brochure (The underlined part "bro" is pronounced differently compared to "pro" in profit, "lo" in local, and "fo" in follow)

I hope this helps!