緊急求教: 給父母經濟擔保的I-134表格

請教:
1. 邀請父母一起來, 需要兩份還是一份I-134?
2. I-134表第一項如下: (本人是綠卡身份, 不是公民, 需要填以下選項目麽)

If you are not a native born U.S. citizen, answer the following as appropriate:
a.If a U.S.citizen through naturalization, give certificate of naturalization numberc.
b. If a U.S. citizen through parent(s) or marriage, give citizenship certificate number
c.If U.S. citizenship was derived by some other method, attach a statement of explanation.
d. If a lawfully admitted permanent resident of the United States, give "A" number
非常感謝!