Write in Terms of I $\sqrt { - 81 }$ A) $9 \mathrm { i }$

Multiple Choice

Write in terms of i.
- $\sqrt { - 81 }$

A) $9 \mathrm { i }$
B) $\pm 9$
C) $- 9 \mathrm { i }$
D) $\mathrm { i } \sqrt { 9 }$