緊急求助！I-485被退。

好不容易等到了排期，遞上了485，又被退回來了。我是主申請人，這次遞的是spouse's 485.

It says:

"Your I-485 Application to Register Permanent Residence or Ajust Status is being returned because it must be demonstrated from the priority date of your approved I-140 that there is a visa available for you from your home country. Please provide evidence that your priority date does have visas available for your home country when you re your application. All other adjustment applications must be filed at the local district office."

請問有誰知道這是怎麽一回事啊？多謝答複！！！
還有在485表的第二項（part 2) Application type
For spouse, which one to choose?


a. an immigrant petition giving me an immediately available immigrant visa number has been approved.
b. my spouse or parent appled for adjustment of status or was granted lawful permanent residence in an immigrant visa category that allows derivative status for spoused and children.