jnu 2014 doubts

[Var1995]

c is the right answer but b option should be correct as well?

[Dr. Strange]

Production possibility frontier is related to supply side of economy i.e labour,technology, productivity,  raw materials etc.  Demand side changes don't affect it.

[Var1995]

is the ans a? it's not the greatest integer fn in the ques right?

[Var1995]

here, as we approach 0 from left, x decreases and approaches 0 but in option b its written x increases and approaches 0. what is the right ans? someone pls clear my doubt.