First let's start with the relationship between grams and centigrams and grams and milligrams.
1 gram = 100 centigrams
1 gram = 1000 milligrams
Because these two equations are equal, we can rewrite our equation as 100 centigrams = 1000 milligrams.
Now we divide by 100 to simplify our equation to 1 centigram = 10 milligrams.
With this simplified equation we see that we multiply the number of centigrams by 10 to find the equal number of milligrams.
Quadrant I or QI
This is tough to explain but here I go
If x and y is positive, it's QI
If x is negative and y is positive it's QII
If x and y are negative, it's QIII
If x is positive and y is negative It's QIV
So the answer is C
Hopes this helps :D