A wire is made from a $3.0\,\text{m}$ section of metal X connected to a $1.0\,\text{m}$ section of metal Y. Its cross-sectional area is constant throughout. When a load is attached to this wire, metal X extends by $1.5\,\text{mm}$ and metal Y extends by $1.0\,\text{mm}$. The same load is then attached to a second wire with the same cross-sectional area, but this time it contains $1.0\,\text{m}$ of metal X and $3.0\,\text{m}$ of metal Y. What is the overall extension of the second wire?
- A$2.5\,\text{mm}$
- B$3.5\,\text{mm}$
- C$4.8\,\text{mm}$
- D$5.0\,\text{mm}$