Let f : R → R be given by $\mathrm{f}\left(\mathrm{x}\right)=5\mathrm{x}\text{. If }\mathrm{x}\in \mathrm{Q}\text{ and }\mathrm{f}\left(\mathrm{x}\right)={\mathrm{x}}^2+6\text{ if }\mathrm{x}\in \mathrm{R}~\mathrm{Q}$, then 

f is continuous at x=3 but not at x=2

f is continuous at x=2 and x=3

f is continuous at x=2 but not at x=3

f is not continuous at x=2 and x=3