Final answer:
Isabella cannot make the trail mix because she doesn't have enough money.
Step-by-step explanation:
To determine how many pounds of trail mix Isabella can make, we need to calculate the cost of each ingredient. She wants to mix one part almonds, two parts walnuts, and three parts raisins. Almonds cost $12 per pound, walnuts cost $9 per pound, and raisins cost $5 per pound. Let's calculate the cost of the ingredients:
- Almonds: 1 part x $12 per pound = $12
- Walnuts: 2 parts x $9 per pound = $18
- Raisins: 3 parts x $5 per pound = $15
The total cost of the ingredients is $12 + $18 + $15 = $45. Since Isabella only has $15 to spend, she can't make the trail mix. Therefore, the answer is none of the options provided.