You would take 8.50 and divide it by 12.
to get $0.71
The answer is A; every x-value must correspond to ONE y-value only. y-values can correspond with as many x-values as they want, but if you see an x-value corresponding with more than one y-value, that's not a function.
It will take 1000 days to spend 1,000,000 if you spend 1,000 per day.