A child fills a pail by using a water hose. After finishing, the child
plays in a sandbox for a while before tipping the pail over to empty it.
If V(t) gives the volume of the water in the pail at time t ,
then the figure below shows V'(t) as a function of t .

At what time does the child:

**A.**
Begin to fill the pail?

**B.**
Finish filling the pail?

**C.**
Tip the pail over?

*(What would the graph of V'(t) look like if the child filled the pail by using a play shovel to repeatedly scoop water from a larger bucket and dump it in the pail instead of using a hose?)*

You can earn partial credit on this problem.