match the idiom with its definition
1. a white collar 
2.a blue collar 
3.working unosocial hours
4.on piecework 
a.)is a manual worker, e.g. in a factory 
b.)a worker recevies payment for the number of pieces produced, not for the length of time he works 
c.)does an office job 
d.) working at inconvenient times, e.g. Sundays, at night, public holidays etc.