Determine Which Number Is in "Proper" Scientific Notation $0.5 \times 10 ^ { 8 }$

Determine which number is in "proper" scientific notation.

A) $0.5 \times 10 ^ { 8 }$
B) $49 \times 10 ^ { 5 }$
C) $2.31 \times 10 ^ { - 4 }$
D) $0.98 \times 10 ^ { 10 }$