Explanation
Let's remember some properties for the exponents
[tex]\begin{gathered} a^m\cdot a^n=a^{m+n} \\ \frac{a^m}{a^n}=a^{m-n} \\ a^{-m}=\frac{1}{a^m} \end{gathered}[/tex]hence
let's calculate the product
[tex]\begin{gathered} 10^4\cdot10^3 \\ 10^4\cdot10^3=10^{4+3}=10^7 \\ 10^4\cdot10^3=10^7 \end{gathered}[/tex]therefore, the answer is
[tex]A)10^7[/tex]I hope this helps you