Would you like to come to dinner tonight?----------------,bu

I‘d like to,but I’m too busy.按语言习惯,能否去,是个客观问题,不存在说"sorry"的.所以,D选项不完美.但,其符合语法,故选D.
would like to是个固定的婉转语气说法,不能简单拆分,故不选A和B.此题原意是说“想,但太忙去不了”,故本身有转折语意,所以后面用了个but,则前半句必然是肯定语气,则按语意逻辑,C也不选.