a)
concentrate = focus,
main source = origin/cause,
widespread = common,
prevent = stop,
attempting = try,
alert = awake,
adverse = unfavourable,
minimise = reduce,
moderate = reasonable amount,
contributes = cause in part,
coping = manage,
slouching = sit in a lazy way
b)
1 improve
2 basis
3 coping
4 weakened
5 moderate
6 concentrate
7 contributes
8 lessen