Paulo has a job printing some certificates on A5, 148 x 210 mm size paper. He then has to post the certificates to the client. Paulo does not want to fold the certificates when he posts them. What is the smallest envelope size that Paulo can use so that he does not have to fold the certificates when he posts them?
C 3 324 x458, C4 229 x 324, C5 162 x 229, C6 114 x 162