enthuware.ocpjp.v7.2.1711

[NandaMin]

Please correct me if wrong.

I'd rather to choose option 1.) It may print any combination of the keys. for that case where 'c' will be never removed and 'a' and 'b' may or may not be seen in second thread.

[admin]

Yes, so in that case c, will be printed. Which is fine as per option 3.