The correct answer here is A.  The Senate did not vote to convict President Clinton on the charges that were levelled against him.  A majority of the Senate voted to convict on one charge and 50% of the Senate voted to convict on the other, but a two-thirds majority is needed.  This is why B is not correct.

The House does not vote on whether to convict a president who is impeached.  The House votes on whether to charge the president--to impeach him.  However, it is the Senate that votes on whether to remove the president from office.  This is why A is correct and D is not.