It can be inferred from paragraph 2 that before t

It can be inferred from paragraph 2 that before the visa regulations were revised,foreign teachers have to______.

A. sign new contracts if they wanted to continue to work

B. go through any formalities if they wanted to stay a bit longer

C. visit a neighboring country if they wanted to renew their visas

D. interview a South Korean official if they wanted to apply for work permits