Although he had to spend lots of money for going to the ball, he accepted the invitation.____,

the ball was important to him. [ ]

A. After all

B. In all

C. First of all

D. Above all

目前光传输网络核心层逐渐向（）方向发展，中继层面快速过渡到以（）为代表的经济传送话音和数据的方式，接入层面逐步向（）过渡。