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