What is the steps to dividing
a. decimal by decimal?

So, it depends on how many decimals are both numbers, but you wanna make sure that the divisor (is that what that called) is not a decimal.
so, if your question is 10.5 / 1.5,
you wanna make sure 1.5 is a whole number,
so you just change 1.5 into 15, by moving the decimal point to the back.
but this is unbalanced. so when you move the decimal point 1 step further, you wanna make sure the number youre dividing does it too.
so there you go, 105 / 15, and calculate that normally.
if your question is 15.015 / 1.5, you don't need to make 10.05 a while number, just make it to 150.15 / 15, as long 15 is a whole number, then ur fine. when you calculate that, follow the picture.

Example : 10.5 / .5
First you would move the decimal point in the point five over leaving it a five, and then move the decimal point  in the 10.5 leaving it 105. Then you would divide normally. Which in the end you would get 21.
(I attached it all drawn out in case this was hard to understand)

The answer should be d.