To determine which type of grape costs more per pound, we can compare the cost of red grapes with the cost of green grapes based on the information provided.
From the equation given for red grapes:
\[ y = 3x \]
This indicates that red grapes cost $3 per pound (when \( x = 1 \)).
According to the chart, green grapes cost $2 per pound.
Now, we can compare the costs:
- Red grapes: $3 per pound
- Green grapes: $2 per pound
Since $3 (cost of red grapes) is greater than $2 (cost of green grapes), we can conclude that:
C. Red grapes cost more per pound.