Choose the correct answer

7.acne is not a serious disease,______young people always want to avoid it
a.because         b.when          c.but             d.and
8.my brother likes running_______cycling
a.so         b.and          c.as         d.or'
9.stand up every hour______do some simple exercise to reduce sitting time
a.since        b.and         c.or            d.but
10.don't eat a lot of meat________snacks.
a.and         b.or           c.so           d.while