Let f(x)    
then
  is continous at x= 0
  is continous from left  at x= 0
  is continous from right at x= 0
Limit exists at x=0 but not equal to f(0)
                
                  As we have learned
Condition for discontinuity -
limit of function at x = a does not exist.
limit exist but not equal to x = a
-
 
For (A) All three are not equal to disconitnous at x=0
For (B) LHL = f(0)  it will be continous from left at x=0
For (C) LHL  f(0) 
 it will be continous from right at x=0
For (D) LHL  RHL  so limit doesn't exist 
Option 1)
  is continous at x= 0
Option 2)
  is continous from left  at x= 0
Option 3)
  is continous from right at x= 0
Option 4)
Limit exists at x=0 but not equal to f(0)
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