$23)$ When a certain string is clamped at both ends, the lowest four resonant frequencies are $50,100,150,$ and $200$Hz$.$ When the string is also clamped at its midpoint, the lowest four resonant frequencies are: A$)50,100,150,$ and $200$ Hz B$)50,150,250,$ and $300$ Hz C$)100,200,300,$ and $400$ Hz D$)25,50,75,$ and $100$ Hz E$)75,150,225,$ and $300$ Hz