Answer:
A
Step-by-step explanation:
The last one is right because it’s per 1 unit or in this case day
To put this into simplest form, you can see what common factors they have. 3 can go into 12, so we can divide 12 by 3.
12÷3= 4
3÷3=1
So 4:1 is the simplest form of 12:3.
Tell me if this helps!!