Try and remember your place values!
An easy way is that smaller numbers, have larger names (im sure there are other ways!)
0.1 - tenths (like how one place value after 1 is tens)
0.01 - hundredths (2 place values after 1 is hundred)
etc.
Also remember that 10 of one place value will be 1 of the next up.
In your case the answer is A.
