Corsa B emission standard

Hi,

Does anyone know if there is any Corsa B that is Euro4?
How does one calculate the emission standards anyway?
It would be really helpful. I'm planning on buying a Corsa, but can't decide to buy a B or C. B is cheaper and if it would be Euro4, it would be great. Otherwise C... but it's more expensive.
I was looking on mobile.de and at many Corsa B the emission standard isn't mentioned. I found two that are Euro3 though...
Is there any Corsa B that is Euro4? And if yes, how can I know?

Thanks in advance :)