1. Let's visualize the problem using a table:
| Anna | Boris | Clara | Daniel | Sum |
| Sprinkles | ? | ? | ? | ? | ? |
| Chocolate sauce | ? | ? | ? | ? | ? |
| Cherry on top | ? | ? | ? | ? | ? |
2. "Three friends chose sprinkles, three chose chocolate sauce, and three chose a cherry."
| Anna | Boris | Clara | Daniel | Sum |
| Sprinkles | ? | ? | ? | ? | 3 |
| Chocolate sauce | ? | ? | ? | ? | 3 |
| Cherry on top | ? | ? | ? | ? | 3 |
3. "The friend who skipped the sprinkles also skipped chocolate sauce." Without loss of generality, let Anna skip those two toppings.
| Anna | Boris | Clara | Daniel | Sum |
| Sprinkles | | ? | ? | ? | 3 |
| Chocolate sauce | | ? | ? | ? | 3 |
| Cherry on top | ? | ? | ? | ? | 3 |
4. This means that since the sum for sprinkles and chocolate sauce is 3, then the other friends all got it.
| Anna | Boris | Clara | Daniel | Sum |
| Sprinkles | | 1 | 1 | 1 | 3 |
| Chocolate sauce | | 1 | 1 | 1 | 3 |
| Cherry on top | ? | ? | ? | ? | 3 |
5. "The friend who skipped chocolate sauce also skipped the cherry." First of all, only one friend could skip the cherry on top, since the sum is 3, and only Anna skipped chocolate sauce. So, Anna skipped the cherry on top too.
| Anna | Boris | Clara | Daniel | Sum |
| Sprinkles | | 1 | 1 | 1 | 3 |
| Chocolate sauce | | 1 | 1 | 1 | 3 |
| Cherry on top | | 1 | 1 | 1 | 3 |
6. Our answer will be:
No topping - 1 and All three toppings - 3.