What Must Occur in Order to Override a Presidential Veto

What must occur in order to override a presidential veto?

A) The bill must be sent back to a joint committee and reworked.
B) Both chambers must reach a 2/3 majority vote.
C) Both chambers will attempt to push through favorable legislation to persuade the president to reconsider the vetoed bill.
D) Both chambers must reach a unanimous vote to override the veto.