Answer:
D. None of these
Explanation:
(5×10^8)(4×10^3)
=20 × 10^11
All the terms are being multiplied. There is no distributive property (FOIL) here. Rearrange the numbers in any order that helps you.
5 × 4 × 10^8 × 10^3
Add exponents to multiply the 10's.
and in proper scientific notation, one last change would give you
2.0 × 10^12