Choose the word whose main stressed syllable is placed differently from that of the other in each group

Exercise 2 : Choose the word whose main stressed syllable is placed differently from that of the other in each group.
A. diverse           B. mountain   C. empty    D. racing 
A. appearance    B. waterfall    C. cathedral    D. essential
A. gallery             B. serious    C. memorial    D. barbecue
A. dangerous      B. natural    C. beautiful    D. delicious
A. pillow              B. towel    C. forest    D. confirm