Answer:
C
Explanation:
Usually rate is determined as a distance over time, where the time is a unit. In other words, we have "1" of the time (for example, 1 hour, 1 second, 1 gallon, etc).
Look at each answer choice:
A: doing 45 crunches in 1 minute
This is definitely a rate because the time (1 minute) is a unit.
B: paying $3.15 for 1 gallon of gas
Again, this is considered a rate because you're paying $3.15 per gallon.
C: folding 6 loads of laundry in 3 days
We can see this isn't a rate because the time is 3 days, not 1. So C is the answer.
D: walking 4 miles in 1 hour
This is a rate because our time is 1 hour.
The answer is C.