Which number is not in scientific notation?
A6 ⋅ 10^ 25 B.2.01 ⋅ 10^ −2 C. 1.3 ⋅ 10^−4 D. 0.5 ⋅ 10^3
A6 ⋅ 10^ 25 B.2.01 ⋅ 10^ −2 C. 1.3 ⋅ 10^−4 D. 0.5 ⋅ 10^3