Answer:
Answer is B
Explanation:
It's not A because we're boiling only water.
It's not C because the last dot for 2 cups ends at 70 min while the last dot for 4 cups ends at 90 min.
It's not D because water boils at around 100 C, as shown in the graph. The highest dot for both 2 cups and 4 cups were about the same near 100 C.
The graph shows that 4 cups of water is able to retain heat more (higher heat capacity), so it takes more time for water to cool down than 2 cups of water.