question_answer

If\[f(x)=\left\{ \begin{align}   & x,\,\,\text{when}\,x\,\text{is}\,\text{rational} \\  & 0\text{,}\,\,\text{when }x\text{ is irrational} \\ \end{align} \right.\]; \[g(x)=\left\{ \begin{align}   & 0,\,\,\,\,\text{when}\,x\,\text{is}\,\text{rational} \\  & x,\,\,\,\,\text{when}\,x\,\text{is irrational} \\ \end{align} \right.\] then \[(f-g)\] is [IIT Screening 2005]

A)                    One-one onto

B)                    One-one not onto

C)                    Not one-one but onto     

D)            Not one-one not onto