Final answer:
The ratio 800g:1kg can be expressed as 1:4.
Step-by-step explanation:
To express the ratio 800g:1kg in the form 1:n, we need to convert both values to the same unit. Since 1kg is equal to 1000g, we can rewrite the ratio as 800g:1000g. Now, we can simplify the ratio by dividing both values by their greatest common divisor, which is 200. This gives us the simplified ratio of 4g:5g.
Therefore, the correct answer is C) 1:4.