Login for hookups app

I'm developing an android app for hook ups with strangers, I understand that Facebook/Twitter login are not appropriate, but between security and flexibility, I'm confused how to register new users, I have the following options:

  1. Google account login (Super easy for Android users, but maybe users do not want to link the ap to his account [thought: I can show message that says their profile will be separate from Google+ activities])
  2. Phone Number (not as straightforward, and users might not want to, but will give me good identity confirmation)
  3. Email (No security and not very good flow, but an option nonetheless)

Which one [or multiple] do I pick, this is an MVP and looking for a point to start from