Answer: A
Explanation: 10^-7 means that the decimal point is 7 digits to the left (the "-" sign) of the 2. Move the decimal point left seven times, putting a "0" for each step. and then place the decimal point. A "0" is added to the left of the decimal point for clarity.
2.98x10^-7
1st) 0.298x10^-6
2nd) 0.0298x10^-5
etc, for 7 times
0.000000298
