B
只有have to 可以和助动词Do 连用.
如果选A ,可以说：Do we need todo exercises every day?
C, D 不能和do 连用.

【俊狼猎英】团队为您解答.I know _____ of those people in the room,so I left.A few B a few C a little D littleWhy is there _____ traffic on the stree today than before?A less B fewer C few D much