Answer B.
A mixed number consists of a whole number plus a part of a number, which would be the fraction. It is relatively easy to switch back and forth between fractions and/or decimals if you just count the places behind the decimal (the end of the whole number).
The number to the left of the decimal point is the whole number, which is nine. The numbers to the right of the decimal point are portions of a whole number. The first position to the right of the decimal would be tenths, the second would be hundredths, and the third would be thousandths. Therefore, you have 3/1000 added to the nine whole number.
