learn/ Son/ for/ four years/ English/  so/ he/ the language/ speak/ well

A. Son was learning the language for four years, so he can speak English quite well.

B. Son has spoken English for four years, so he learned the language quite well.

C. So Son has been learning English for four, he can speak the language well.

D. Son has been learning English for four years, so he can speak the language quite well.