Write the Following Number in Exponential Notation $7 \cdot 7 \cdot 9 \cdot 9 \cdot 9 \cdot 9$

Write the following number in exponential notation: $7 \cdot 7 \cdot 9 \cdot 9 \cdot 9 \cdot 9$

A) $( 7.9 ) ^ { 6 }$
B) $2 \cdot 7 + 4 \cdot 9$
C) $2 \cdot 7 \cdot 4 \cdot 9$
D) $2 ^ { 7 } \cdot 4 ^ { 9 }$
E) $7 ^ { 2 } \cdot 9 ^ { 4 }$