The diagram depicts a steel wire fixed at one end. At the free end, a weight is hanging from the wire over a pulley. A vibrator is fitted to the wire close to the fixed end. A stationary wave containing one loop is formed. The vibrator operates at frequency $f$. Which frequency should be chosen to form a stationary wave with two loops?
- A$\frac{f}{4}$
- B$\frac{f}{2}$
- C$2f$
- D$4f$