Express the Radical in Simplified Form $\sqrt{-864}$ A) Not a Real Number
B)

Multiple Choice

Express the radical in simplified form.Assume that all variables represent positive real numbers.
- $\sqrt{-864}$

A) Not a real number
B) $-12 \sqrt{6}$
C) $-12 \sqrt{-6}$
D) $12 \sqrt{6}$