static credit check vs. credit limit check

Hi experts,

In OVA8, static credit check is activated. In OVAK, which "credit limit check" should be selected properly? I have tried A, B, C, D in OVAK and found FD32 can be updated accordingly. Why?

Plz advise. Many thanks.

ps. A means Run simple credit limit check and warning message

B means Rund simple redit limit check and error message

C means Run simple credit limit check and delivery block

D means Credit management: Automatic credit control