How Was Abu Bakr Chosen as Sadiq?

The question that arises is, how was Abu Bakr as Sadiq chosen? What was the methodology of his choosing? There are three opinions, if you like, about this issue within Sun, Nizm. Some group will say, the Sahaba realized he was the best, so they chose him to be the Khalifa. The second opinion says, the Prophet SallAllahu Alaihi Wasallam subtly indicated that he should be the KhalIFA. And the third opinion is what's left now.