what does the downward slop of ppc indicates?

subject: economics

The downward slope of PPC shows for the production of every additional unit of one good, more and more units of other good has to be sacrificed. This is known as Marginal Rate of Transformation (MRT) or Opportunity Cost.

It should be noted that as we move down along the PPC, the slope of PPC (or MRT) increases. This suggests that as the production increases, to produce each additional unit of one good, more and more units of other good needs to be sacrificed. In other words, the opportunity cost increases.