The function $$\mathrm{f}(x)=[x] \cdot \cos \left(\frac{2 x-1}{2}\right) \pi$$, where $$[\cdot]$$ denotes the greatest integer function, is discontinuous at
- Aall irrational numbers $$x$$.
- Bno $$x$$.
- Call integer points.
- Devery rational $$x$$ which is not an integer.
✓ Correct answer: C
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