Answer:
E
Explanation:
Here’s a tree diagram that represents the total outcomes for selecting two stones by choosing a white stone first and a red stone second:
Start
|
|
______|______
| |
| |
White 1 White 2
| |
| |
___|___ ___|___
| | | |
| | | |
Red 1 Red 2 Red 1 Red 2
There are two branches at the first level representing the two possible choices for the white stone. For each of these branches, there are two branches at the second level representing the two possible choices for the red stone. So there are a total of 2 * 2 = 4 possible outcomes: (White 1, Red 1), (White 1, Red 2), (White 2, Red 1), and (White 2, Red 2).