Giving reason, comment on the shape of PPC based on the following table:
`{:("Good X (units)",0,1,2,3,4),("Good Y (units)",20,18,14,8,0):}`

Explanation

It is clear from the above table that MOC of producing more of 'X' in place of 'Y' is increasing. Thus PPC would be a downward sloping concave to the origin.