Which answer shows 0.00897 written in scientific notation?

That would be 8.97 x 10^-3

We use the decimal system and the values for decimal places start at 10^-1 and decrease in power by one for each place you move further to the right..ie  10^-2, 10^-3, etc  which is equal to 1/10, 1/100, 1/1000 etc so if you move the decimal point to the right three times to move it just past the 8 you are at the column with coefficient equal to 10^-3 so the number in scientific notation is:

8.97X10^-3