Use the Product Rule to Multiply $\sqrt [ 4 ] { 16 } \cdot \sqrt [ 4 ] { 81 n ^ { 4 } }$

Multiple Choice

Use the product rule to multiply. Assume all variables represent positive real numbers.
- $\sqrt [ 4 ] { 16 } \cdot \sqrt [ 4 ] { 81 n ^ { 4 } }$

A) $- 6 n$
B) $6 n$
C) $- 1 \mathrm { n }$
D) $5 \mathrm { n }$