My understanding of the PPF is that the slope relative to the x-axis represents the opportunity cost (of the good on the x-axis), while the opportunity cost of the good on the y-axis is 1/slope.

For this question, as more albums are produced, we are moving from left to right along the x-axis, where the slope is decreasing in absolute magnitude. This would imply that the opportunity cost of the y-axis good is increasing. However, the answer key states the exact opposite.

i ask gemini, chatgbt and deepseek they all say the answer khan academy gave me is wrong. But I'm a only a beginner I just can't trust myself
Appreciate any advice thanks.