Anthros what are those and if I apply to SNA I can go to either jets or helicopters
Anthropometrics are the measurements of your body, essentially. Things such as elbow to tip of fingers, butt to knee, length of leg fully extended, max reach, etc. Because of your anthro measurements you may be suitable for some platforms and not others. For example, your butt to knee measurements may be too long to fly a Prowler, but it might be just fine for Hornets or Harriers.
You may select Jets, Helicopters, or Maritime upon completing primary flight training. Based upon the needs of the service, your performance, and your desires (in that order) you may or may not get what you want.