H4 EAD RFE under C(36)

[raj4dotnet]

Hi Folks

I am on H1B and working for client. My I-140 approved on 09-07-2016. And I have I-129 is valid from 08/19/2017 to 04/18/2020. I never applied for I-765.  Recently my elder unmarried son completed 18 yrs. And he want to work while study. And currently studying in community college. 

I applied for my son EAD. Prepare I-765 and put eligibility category C(36) as this is for unmarried child of principal beneficiary. His filing fee check is clear from bank. Also finger print is completed. But USCIS send RFE as per below

"Submit evidence that principal applicant has been granted employment authorization under classification (C)(35). This evidence should be in the form of an approval notice of a copy of the front and back of the principal applicant's Employment Authorization Document"

I have below questions

1. As per USCIS RFE do I need approved I-765?
2. Am I used C(36) as application category for my son in I-765 is correct?
3. what document should be response for RFE? 

[adshah84]

As I know H4 EAD is only for spouse. I might be wrong but please confirm. 

[pontevecchio]

H4 EAD is only applicable to spouses.