Answer:
The graph which represents Jack and Jill's number of pails over time is:
-  graph of line going through (1,7) and (3,11) 
Explanation:
It is given that:
Jack and Jill had 5 pails of water. Each trip up the hill, Jack and Jill obtained 2 more buckets of water. 
Let x be the number of hills they tripped.
and y denote the number of buckets of water they have.
Then the equation which represent the relationship between y and x is:
 

On making a table for x and y:
  x y
 1 7
 2 9
 3 11
 4 13
 5 15
 6 17
 Hence, the graph will pass through the points (1,7) (2,9) (3,11) (4,13) (5,15) (6,17) and many more.