Let c be the cost of parking.
Let t be time in hours.
1a.
When we change the time t, the cost will get changed.
That is, cost (c) is depending on time (t).
So, the independent variable is t and the dependent variable is c.
1b.
In sentence, the cost of parking (c) is a function of time (t).
1c.
Suppose it cost $3 per hour to park, with a maximum cost of $12.
From the graph, we observe that
Each input values gives the single output value.
Hence,
Yes, this graph represents this function.