Suppose function `k` gives the volume of water in a pool (in liters) in terms of the number of minutes, `t`, that have elapsed since you started filling that pool.

`k` represents:

the output of the function

the volume of water in the pool in liters

the name of the function

the number of minutes that have elapsed since you started filling the pool

None of the above

Use function notation to represent the volume of water in the pool `21` minutes after you started filling it up.

Use function notation to represent the volume of water in the pool `83` minutes after you started filling it up.