— It’s good to see you again,Agnes.

B. you returned
since 后面都是加时间点.
The 2004 earthquake which triggered the Asian tsunami was the third biggest quake since 1900.
There have been many changes since the war.
从战争到现在发生了许多变化.
It has been raining since morning.
从早晨到现在一直在下雨.
She has rung me once since she left.
她离家后给我来过一次电话.
I've been busy ever since I came back.
自我回来后一直在忙.
由以上例句可知：本题也是选择一个时间点.
那么自然是过去的一个时间,因为前面这句
This has been our first chance to visit ,
用了完成时,自然是发生在过去.
只有B是过去时.

B since 后接一般过去时的句子

B

since +从句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.
延续动词 一般用过去式
连续动词 用完成时
B
望采纳！