What is 3.5x10^2 x 8.0x10^-2 in scientific notation

Scientific notation is defined as writing a number between 0 to 10 multiplied by a power of 10
3.5 x 10² x 8.0 x 10⁻²
when we solve the equation 
answer - 28 
to write in scientific notation the decimal point should come after the first digit from the right. to bring the decimal point from after digit 8 to after digit 2, we have to move one decimal place to the left. then we get 2.8, to get the value as 28 we have to multiply 2.8 by 10
therefore answer is 
2.8 x 10¹

The answer for this question is d. none of these

Answer) by studying proton collisions hope this : )