The president has nominated the next ambassador to canada what must happen before the ambassador can take officea. take a new vote in the senateb. get the approval of congress c. ask him to state his economic policyd. check in with the president who hired him

The correct answer is A (TAKE A NEW VOTE IN THE SENATE). Once the president of the United States nominates a candidate for Ambassador, the Senate must confirm the nomination, and, once it is confirmed, the president appoints him or her. This is stated in US Constitution, Article II, Section 2.  

most likely,

a. take a new vote in the Senate