The following sentence contains a grammatical error. Select the option that correctly rectifies the error.
He sees us coming, and unaware that we had learned of his treachery, greeted us with a smile

A

He saw us coming, and unaware that we learned of his treachery, greeted us with a smile.

B

He saw us coming, and unaware that we had learned of his treachery, greeted us with a smile.

C

He saw us coming, and unaware that we were learning of his treachery, greeted us with a smile

D

He saw us come, and unaware that we had learned of his treachery, greets us with a smile.