Which of these expressions is in the simplified form?

Answer:
C!
Step-by-step explanation:
A) can be simplified into -> (x ([tex]\sqrt{3}[/tex] * x - 3*[tex]\sqrt{3y}[/tex])/3)
B) Can be simplified into ([tex]\sqrt{2x}[/tex]/2) + ([tex]\sqrt{2z}[/tex]/2)
D) Can be simplified into 5*[tex]\sqrt{5x}[/tex] - x^2
Therefore, C is the correct answer because it cannot be simplified any further!
Hope this makes sense!!!!
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