The united states began sending large numbers of military advisers to south vietnam after which had occured

The correct answer is H.o Chi Minh began supplying and supporting communists in the south.

H.o Chi Minh started sending support to communists in the south with the goal being to fight in the south against each other while he was pressuring the south from the north. When the US realized this, they sent military envoys to help with equipment and advisers who would train southern soldiers and this escalated the war.