An increase in body fluids leads to an increase in kidney filtration which leads to an increase in kidney output (urine). What type of feedback is this?

Positive feedback.

Explanation:

An increase in body fluids causes increase in kidney filtration which leads to higher production of urine, this type of feedback is known as positive feedback because when there is increase in the output, this is called positive feedback while on the other hand when there is decrease in the output we called it negative feedback. So we can see that the output of the kidney is higher concentration of urine so we can say that it is a positive feedback.