Ans: C
Since the mode of the seven numbers is $8$, then $a=b=8$. Rearrange the seven numbers in ascending order, we have
Since the mode of the seven numbers is $8$, then $a=b=8$. Rearrange the seven numbers in ascending order, we have
$$1,\ 3,\ 7,\ 7,\ 8,\ 8,\ 8$$
Therefore, the median of the seven numbers is $7$.
