Express the Number in Terms of I $\sqrt { - 9 }$

Multiple Choice

Express the number in terms of i.
- $\sqrt { - 9 }$

A) $\sqrt { 3 } \mathrm { i }$
B) $- \sqrt { 3 } \mathrm { i }$
C) $- 3 \mathrm { i }$
D) $3 \mathrm { i }$