Choose the word whose main stress is placed differently from the others

I.      Choose the word whose main stress is placed differently from the others.  
1.      a) novel                      b) comprise               c) cotton                    d) label
2.      a) separate                 b) friendliness          c) tropical                  d) religion
3.      a. blanket                                b. language           c. campus                d. bamboo
4.      a. gather                                   b. relax                 c. collect                  d. exchange