My app is a sync solution (imagine dropbox). The user needs to sign in to access the app\'s features, and if he does not have any account already created, he can sign up.
Apple does not allow apps that require you to share person information to work, like an e-mail address.
You options are, remove the need for an e-mail address or remove account creation form you app and move it to a website.
It also states that you app is asking to create an account to access the full app and even needs the account or acces features that do not require the user to have an account. You can make those features available with out the account creating you might be able to get thru the review.
The reason apps like Facebook and Dropbox got thru the review proces is because they don't have a register option which is in app only. They redirect to a website.