imc

The only digits available to use in the phone number are $2$, $3$, $4$, $5$, $6$, $7$, $8$, and $9$. There are only $7$ spots left among the $8$ numbers, so we need to find the number of ways to choose $7$ numbers from $8$. The answer is then $\left(\genfrac{}{}{0ex}{}{8}{7}\right)=\frac{8!}{7!(8-7)!}=\boxed{\text{(D) }8}$ Alternatively, we could just choose $1$ out of the $8$ numbers not to be used. There are obviously $\boxed{8}$ ways to do so. Note: for each combination of 7 numbers, exactly 1 is in increasing order