Simplify the Expression $\sqrt { 15 } \cdot \sqrt { 48 }$

Multiple Choice

Simplify the expression. Assume all variables represent positive real numbers.
- $\sqrt { 15 } \cdot \sqrt { 48 }$

A) $20 \sqrt { 3 }$
B) $12 \sqrt { 5 }$
C) $- 20 \sqrt { 3 }$
D) $- 12 \sqrt { 5 }$