A teacher asks three students to write an equation for finding the total resistance $R_C$ of resistors with resistances $R_Y$ and $R_Z$. Which students are right? Student 1: $\frac{1}{R_C}=\frac{1}{R_Y}+\frac{1}{R_Z}$. Student 2: $\frac{1}{R_C}=\frac{1}{R_Y+R_Z}$. Student 3: $R_C=\frac{1}{R_Y}+\frac{1}{R_Z}$.
- A1 and 2
- B1 only
- C2 and 3
- D3 only