Choose the word whose underlined part is pronounced differently

Choose the word whose underlined part is pronounced differently.
16(s). A. manages B. laughs C. photographs D. makes
17(ei). A. eight B. weight C. height D. freight
18(i). A. contribute B. tiny C. disaster D. investigate
19(a). A. nature B. native C. natural D. nation
20(c). A. compete B. decide C. announce D. necessary