I was checking the graphical presentation and there it was described. But I noticed that it always goes down. The figure presentation is from class 12 NCERT economics chapter 2. Can you tell me the reasons?

The term used in the second chapter Consumer’s equilibrium and Demand from 12th class NCERT explanation. While reading the paragraph it was mentioned there. I didn’t found the proper definition or meaning of this word.

I am in class 12th from Arts stream. for year 2022-2022. While doing self preparation I found this question in my class 12th NCERT solutions book. Among practice paper. I was wondering if I could get answer for this too.