YOUR RFE requested you demonstrate that how the national interest would be adversely affected if you were asked to go throug LC process.
Specifically, you need to do the following things:
1) 4-6 independent letters
2) collect any availabe unsubmiited evidence existing prior to your first submission date (as defined explicitly in your RFE)
3) compose your RFE rsponse letter, stressing on the INFLUENCES or IMPACTS of your work on national interest (using recom letter as evidence) and on your peers' work (such as citation, and/or other similar evidence).
Just for your reference!! GOOD LUCK