What does "Por el que" mean here? I have to do a translation assignment and I can't work out what "Por el que" means at the start of a sentence. I tried googling it but all the examples are in the middle of sentences, in which case it means "which", but it doesn't quite work here. "Por el que son necesarios planes integrales contra la exclusión social de carácter transversal, que actúen en el conjunto de los sistemas y servicios del Estado del Bienestar."