Answer:
1. Vanilla
2.Strawberry
3.Chocolate
4.CS
5.VV
6.SS
Explanation:
For these problem you are solving to find ALL of the possible outcomes with the 3 flavours.
1. They already have a combination for Chocolate-chocolate and Chocolate-Strawberry. The only flavour you haven't used yet is vanilla which makes your first answer vanilla.
2. They already have a combination for Vanilla-Chocolate and Vanilla-Vanilla. The only flavour you haven't used yet is Strawberry which makes your answer strawberry.
3. They already have a combination for Strawberry-Vanilla and Strawberry-Strawberry. The only flavour you haven't used yet is chocolate which makes your answer chocolate.
So when looking at the letters they are honestly just initials to the combinations possible. The order of the letters depend on what words come first going down your branch.
4. The two words are chocolate and strawberry. The first letter in both words are C and S so the answer is CS.
5. The two words are vanilla and vanilla. The first letter in both words are V and V so the answer is VV.
6. The two words are strawberry and strawberry. The first letter in both words are S and S so the answer is SS.