Simplify the Expression $\sqrt { 15 } \cdot \sqrt { 27 }$

Multiple Choice

Simplify the expression. Assume all variables represent positive real numbers.
- $\sqrt { 15 } \cdot \sqrt { 27 }$

A) $- 15 \sqrt { 3 }$
B) $9 \sqrt { 5 }$
C) $15 \sqrt { 3 }$
D) $- 9 \sqrt { 5 }$